Report of the
Herbaceous Ornamental Crop Germplasm Committee
September 1, 1995
1. Introduction
Herbaceous ornamentals are cultivated worldwide and comprise a vast number
of genera, species, and hybrids. Most of the floricultural crops grown commercially
are herbaceous rather than woody plants, with a few notable exceptions such
as azalea (Rhododendron sp.), florists' hydrangea (Hydrangea macrophylla),
rose (Rosa sp.), and several foliage plants. Thus, herbaceous ornamentals
and floricultural crops can generally be considered synonymous terms.
The genetic resources of herbaceous ornamentals have not received as much attention
as most other horticultural and agronomic crops, and this is probably due to
three reasons: 1) ornamentals serve an aesthetic function and do not render
food, clothing, or shelter; 2) herbaceous ornamentals comprise numerous taxa;
and 3) its genetic resources are utilized by several different user groups.
However, statistical data indicate that herbaceous ornamentals are a major agricultural
commodity in the United States. According to the USDA's Economic Research Service,
the greenhouse/nursery (G/N) sector is the sixth largest agricultural commodity
group in the United States and accounted for 11 percent of all farm crop cash
receipts in 1991 (Johnson, 1992). Grower cash receipts for greenhouse, nursery,
and turfgrass products totaled $8.4 billion in 1991, exceeding receipts for
all food grain crops by $1.6 billion and were 67 percent higher than the combined
values of all sugar and tobacco crops. Floriculture products account for approximately
39 percent of G/N receipts whereas nursery and turf products account for approximately
61 percent of G/N receipts (Johnson, 1992). Thus, the economic value of floricultural
crops is comparable to m any "essential " crops. However, the fraction
of federally-funded research dollars spent for research on all G/N crops is
a mere 0.02 percent (Johnson, 1992). It is also important to note that commercial
growers of floricultural crops do not receive direct support from the federal
government through production control programs, price supports, or import quotas.
G/N crops play a major role in the economies of several states. G/N crops are
produced in all 50 states and rank in the five top commodity groups in 21 states
(Johnson, 1992). It is the second largest commodity group in California and
Florida. Greenhouse and nursery products are the second largest commodity in
the New England region and accounted for 39 percent of total crop sales in 1991
(Staff of the New England Agricultural Statistics Service, 1993). Cash receipts
for New England-grown greenhouse and nursery products totaled $391.2 million
in 1991. By comparison, cash receipts for New England-grown potatoes and fruit
(apples, blueberries, cranberries, etc.) totaled $115.3 million and $210.3 million,
respectively, in 1991.
The wholesale value of floricultural crops reached $3.23 billion in 1994, a
5 percent increase above the 1993 level and a 7 percent increase above the 1992
level (Agricultural Statistics Board, 1995). These figures do not represent
the total domestic output of floricultural crops, but only the output from growers
in 36 surveyed states with gross sales in excess of $10,000 annually. The 1994
wholesale value for the four major floricultural commodity groups was as follows:
1) $559 million for cut flowers and greens (19% of total); 2) $654 million for
potted flowering plants (22% of total); 3) $487 million for foliage plants (16%
of total); and 4) $1.28 billion for bedding and garden plants (43% of total)
(Agricultural Statistics Board, 1995).
II. Present Germplasm Activities
Herbaceous ornamental genetic resources are utilized by several public and
private institutions in the United States. Institutions that are directly involved
in utilization of herbaceous ornamental germplasm include: 1) components of
the USDA's Agricultural Research Service (ARS), such as the United States National
Arboretum and the Florist and Nursery Crops Laboratory; 2) state agricultural
experiment stations (AES) and departments within land-grant universities; 3)
private-sector companies with breeding and cultivar development programs, or
interest in pharmaceutical or industrial uses of plants; 4) public and private
botanical gardens; and 5) special-interest plant societies such as the American
Begonia Society and the American Plant Life Society.
Many public institutions have active programs in germplasm enhancement and/or
cultivar development of herbaceous ornamentals, including the USDA Florist and
Nursery Crops Laboratory, University of California, Colorado State University,
University of Connecticut, Cornell University, University of Florida, University
of Hawaii, University of Illinois, Iowa State University, University of Massachusetts,
Michigan State University, University of Minnesota, University of Nebraska,
The Ohio State University, The Pennsylvania State University, Purdue University,
and University of Wisconsin (Cathey, 1987). Private companies in the United
States with herbaceous ornamental breeding programs include Bodger Seeds Ltd.
(Lompoc, CA), W. Atlee Burpee & Company (Warminster, PA), B.L. Cobia Inc.
(Winter Garden, FL), Denholm Seed Company (Lompoc, CA), Paul Ecke Ranch (Encinitas,
CA), Goldsmith Seeds (Gilroy, CA), Holtcamp Greenhouses Inc. (Nashville, TN),
Mikkelsens Inc. (Ashtabula, OH), Oglesby Nursery Inc. (Hollywood, FL), PanAmerican
Seed Company (W. Chicago, IL), Waller Flowerseed Company (Guadalupe, CA), and
Yoder Brothers Inc. (Barberton, OH). Although many public and private institutions
are involved in germplasm enhancement and cultivar development, the acquisition
of herbaceous ornamental germplasm from centers of diversity or other world
locations has been limited. In addition, minimal effort has been devoted to
screening accessions for important horticultural traits and accurately describing
herbaceous ornamental germplasm in National Plant Germplasm System (NPGS) collections.
III. Status of Crop Vulnerability
Crop vulnerability and genetic erosion of herbaceous ornamentals are major
concerns for plant breeders and commercial growers. Whereas a large diversity
of floricultural crops are grown commercially, many of these crops have been
developed from a very narrow germplasm base. Most of the floricultural crops
grown currently were developed during the mid to late 1800s and early 1900s
by European breeders using, in many cases, a few specimens obtained from plant
collectors, nurseries, or botanical gardens. In the past 40-50 years, ornamental
plant breeders have used few wild or unimproved species as a germplasm source
but, instead, have relied on genetic variation within segregating cultivars
(Ewart, 1981). Domesticated materials (breeding lines, clones, and cultivars)
will always remain an important germplasm source, but may not contain the genes
necessary for pest resistance or improvement of other traits. Acquisition of
new germplasm is critical to plant breeders and will be required for continued
crop improvement. It is likely that the genetic diversity found in wild or unimproved
germplasm will play an increasingly integral role in floricultural breeding
programs, and breeders will turn to accessions or plant introductions for use
in crop improvement programs.
As with other plants, floricultural crops are susceptible to attack from many
pests, including insects, mites, nematodes, viruses, fungi, and bacteria. Commercial
flower growers are constantly searching for environmentally-safe and cost-effective
methods of pest control that are not damaging to the finished product or the
customer (American Floral Endowment,. 1987). Many of these pest problems may
be diminished or eliminated through plant breeding. Breeders are more likely
to identify sources of pest resistance in a diverse germplasm collection that
includes wild or weedy relatives than among an array of commercial cultivars.
Hence, genetic diversity increases the probability that genes conferring resistance
can be identified for germplasm enhancement or cultivar development programs.
One of the primary objectives of this Crop Germplasm Committee (CGC) is to
assess the quality of the herbaceous ornamental germplasm in the NPGS and make
recommendations for broadening and strengthening the germplasm base via additional
exploration, acquisition, and evaluation. A recent survey of NPGS holdings of
herbaceous ornamental germplasm held at Plant Introduction Stations and Clonal
Germplasm Repositories reveals the following: 1) current NPGS holdings of potentially-useful
species are, in most cases, represented by a single or a few accessions; 2)
nearly all herbaceous ornamental germplasm consists of seed-propagated items
and very few accessions are asexual propagules; 3) few accessions represent
material collected from centers of diversity and/or origin; 4) many of the major
floricultural crops are not represented by a single accession; and 5) some NPGS
sites lack qualified personnel to assess germplasm for its potential as herbaceous
ornamentals. Outside of the NPGS, there are few collections of herbaceous ornamental
crops with 4 broad germplasm base. As a consequence, the vulnerability of many
floricultural crops is considerable. There is an immediate need to correct the
inadequacies of the herbaceous ornamental collections in the NPGS.
V. Current Status and Needs:
Priority Genera. Since herbaceous ornamentals comprise a vast number of genera
and species, the CGC encourages the NPGS to focus on developing comprehensive
collections for a few important genera rather than have incomplete collections
for many genera. The CGC recommends that the following 24 genera be given the
highest priority for collection by the NPGS:
Genus |
Family |
Number of Species,
Center(s) of Diversity |
Ageratum |
Compositae |
approx. 43; N., Central, & S. America |
Alstroemeria |
Alstroemeriaceae |
approx. 60; Brazil, Chile, & Peru |
Aster |
Asteraceae |
250-500; N. & S. America, Europe, Asia |
Begonia |
Begoniaceae |
> 1200; tropics & subtropics worldwide |
Caladium |
Araceae |
approx. 15; tropical America |
Catharanthus |
Apocynaceae |
approx.7; E. Hemisphere tropics (Madagascar to India) |
Dendranthema |
Asteraceae |
40; Europe & Eastern Asia |
Dianthus |
Caryophyllaceae |
approx.300; Europe & Asia mostly, S. Africa |
Dieffenbachia |
Araceae |
approx. 30; tropical America |
Euphorbia |
Euphorbiaceae |
> 1600; W. Hemisphere (sp. of interest) |
Eustoma |
Gentianaceae |
approx. 3; southwest U.S to northern S. America |
Hemerocallis |
Liliaceae |
approx.15; central Europe to China & Japan |
Hippeastrum |
Amaryllidaceae |
approx. 60; tropical America |
Impatiens |
Balsaminaceae |
approx. 600-1000; tropical Asia & Africa (mostly) |
Kalanchoe |
Crassulaceae |
approx. 125; Africa & Madagascar |
Liatris |
Asteraceae |
approx. 32; North America |
Lilium |
Liliaceae |
approx. 70; temperate N. hemisphere |
Lobelia |
Lobeliaceae |
approx. 375; tropical and warm-temperate regions |
Pelargonium |
Geraniaceae |
approx. 250; S. Africa |
Petunia |
Solanaceae |
approx. 30; S. America |
Spathiphyllum |
Araceae |
approx. 35; Mexico; Central & S. America; Phillippines |
Verbena |
Verbenaceae |
approx. 200; W. Hemisphere tropics & subtropics |
Zantedeschia |
Araceae |
6; S. Africa |
Zinnia |
Asteraceae |
approx. 20; N., Central, & S. America |
The CGC unanimously recommends that the NPGS initially emphasize herbaceous
ornamental germplasm collections that can be maintained as seed, but develop
repositories for clonally-propagated herbaceous ornamentals as a long-term goal.
In addition, the committee strongly recommends that a list of ARS-approved explorations
be forwarded to the Herbaceous Ornamental CGC chair on a timely basis. This
would permit the GC to make suggestions to trip participants regarding the collection
of endemic herbaceous ornamental germplasm.
Germplasm collection. In most cases, botanical gardens or other existing plant
collections are the primary sources of germplasm for new floricultural crops
(Christensen and Friis, 1987; Klougart, 1987). However, plant exploration will
be required for developing the NPGS collections and also for obtaining germplasm
for "new" crops. The joint expedition by Longwood Gardens (Kennett
Square, PA) and the USDA to New Guinea in 1970 demonstrates the importance and
economic impact of "new" crops germplasm. This expedition resulted
in the collection of several Impatiens species (Arisumi and Cathey, 1976), and
this germplasm has been transformed into a major floricultural crop: the New
Guinea
Impatiens. In the past 20 years, several USDA-sponsored expeditions have concentrated
on the collection of woody ornamental germplasm (Cunningham, 1990), but the
collection of herbaceous ornamental germplasm by USDA-sponsored expeditions
has been very limited. There is a critical need to recollect the species that
are the progenitors of the world's major floricultural crops and also to collect
new species which may be tomorrow's "new" crops.
Specific recommendations for the collection, evaluation, enhancement, and preservation
of germplasm are provided in the synopses for each priority genus (Section VI).
V. Literature Cited:
Agricultural Statistics Board. 1995. Floricultural Crops: 1994 Summary. USDA,
National
Agricultural Statistics Service. 117 pp.
American Floral Endowment. 1987. Research Priorities for Floriculture. Report
of the
National Research Priorities Summit. 19 pp.
Arisumi, T. and Cathey, H.M. 1976. The New Guinea impatiens. HortScience 11:2.
Cathey, H.M. 1987. Directory 3 of Research Skills for Floriculture. The Ohio
State University, Columbus, Ohio.
Christensen, O.V. and Friis, K. 1987. Research and development of unknown
new pot plants. Acta Horticulturae 205:33-37.
Cunningham, 1. 1990. Collecting landscape plants in eastern Asia. Diversity
6(3&4):22-23.
Ewart, L. 1981. Utilization of flower germplasm. HortScience 16:135-138.
Johnson, D.C. 1992. Recession impacts and economic outlook for the U.S. nursery,
greenhouse, and turfgrass industries. In: Papers presented at the U.S. green
industry session, 'Trends, Issues, and Policy Impacts for Greenhouse, Turf,
and Nursery Agriculture", December 2, 1992.
Klougart, A. 1987. Exploration, adaptation, evaluation, amelioration. Acta
Horticulturae 205:3-11.
Staff of the New England Agricultural Statistics Service. 1993. New England
Cash Receipts.
USDA, National Agricultural Statistics Service, Concord, NH.
VI. Synopses for Priority
Genera
AGERATUM (Asteraceae)
Introduction:
The genus Ageratum consists of approximately 43 species of annual or
perennial herbs and shrubs, all native to Central and South America. One species,
A. houstonianum Mill., is an important bedding plant with a domestic wholesale
value of approximately $20 million. Capitula have tubular florets that are mostly
in shades of blue, but can be pink or white. Inflorescences consist of five
to fifteen capitula in (usually) loose clusters. The leaves are opposite, ovate
to cordate, and sometimes downy. Plant height varies from 20cm to Im. The short
material has a tendency to mutate in stem length with elongated internodes.
The species is an annual herb and is indigenous to Mexico. The chromosome number
is 2n 20.
Present Germplasm Activities:
Most of the breeding work with A. houstonianum has been performed by
private industry. There are some vegetatively-propagated cultivars offered in
the trade, but most of the cultivars are propagated from seed. The seed-propagated
cultivars in the commercial trade are predominantly F1 hybrids. Hybrid seed
is usually produced using self-incompatible clones as seed parents. A disadvantage
with this system is that the selected parent lines usually have to be maintained
vegetatively.
'Blue Blazer' was the first commercial F1 hybrid to be produced, and was bred
by Goldsmith Seeds using two self-incompatible parents. This F1 hybrid exhibited
significant improvements over open-pollinated cultivars, including better plant
uniformity, vigor, and earlier bloom with dependable seed production. In 1966,
Charles Weddle discovered malesterile plants within a population of 'Blue Carpet'.
A selection from this material was used as the male sterile parent for the excellent
cultivar 'Blue Danube'. 'Blue Mink' is an open-pollinated, tetraploid cultivar
of A. houstonianum. 'Blue Horizon' is a new tall, cut flower cultivar
which is a triploid F1 hybrid.
Status of Crop Vulnerability:
The status of indigenous populations is unknown because germplasm collecting
has not been done recently. The genetic diversity within commercial cultivars
of A. houstonianum is expected to be low. Selection of specific characteristics
to meet commercial interests intensified the use of self-incompatibility. This
has narrowed the germplasm base even further. It is very difficult to obtain
highly homozygous inbreds by self-pollination. Most material is self-incompatible
after 3 or 4 generations. The resulting selected material, vegetatively propagated,
is very prone to loss due to viruses and other diseases.
Germplasm Needs:
A. Collection - Emphasis should be placed on collecting seed from indigenous
populations of A. houstonianum and other Ageratum species. The
preservation of commercial hybrids should be a low priority. Current NPGS holdings
of Ageratum include five seed accessions (one A. conyzoides L. and four
of A. houstonianum) that are held at NE-9 (the priority site for Ageratum).
B. Evaluation - Plant introductions should be evaluated for the following
characters: plant height, habit, and vigor; foliage size, shape, and color;
capitulum diameter; flower color; bloom duration and capacity for reflowering;
fertility; and resistance to white fly, aphids, and spider mites
C. Enhancement - Germplasm enhancement activities should be subordinate to
collection, evaluation, and preservation of germplasm.
D. Preservation - Ageratum houstonianum is cross-pollinated and has
a sporophyticallycontrolled self-incompatibility system. Plant introductions
thus require isolation during seed production in order to maintain purity, and
several genotypes are needed for intercrossing within PIs.
Recommendations:
Priority of Actions - Germplasm of Ageratum species (including A.
conyzoides and A. houstonianum) needs to be collected from
several indigenous populations. The collected material needs to be thoroughly
evaluated in replicated trials for horticultural traits. Ageratum is
cross-pollinated and therefore each accession must be isolated during seed increases
in order to maintain genetic purity.
Researchers that may be contacted for additional information:
Yoshiro Arimitsu, Bodger Seeds, Ltd., El Monte, CA
Ageratum Synopsis Prepared by:
Yoshiro Arimitsu, Bodger Seeds, Ltd., El Monte, CA
BEGONIA (Begoniaceae)
Introduction:
Begonia is a large genus that includes at least 1,200 species. The primary
center of diversity for the genus is the neotropics (Mexico to Argentina); a
second center of diversity is in southcentral Asia (India, Sri Lanka, and China).
Some species also are native to the southern, southeastern, and western parts
of Africa. Few plant families exhibit the diversity in size, growth habit, and
foliage morphology that is found within the genus Begonia. Among Begonia
species, height ranges from 5 cm to 2 m. Leaves range in size from under 2 cm
to over 50 cm. The leaf surfaces vary from glabrous to densely hairy. The inflorescences
are usually axillary and dichasial. Flowers are characteristically monoecious,
and the pistillate flowers have inferior ovaries. Flowers are predominantly
white, but may be pink, red, orange, or rarely yellow. The fruit is either papery,
leathery, or fleshy. The basic chromosome numbers (x) for the genus are 6, 7,
and 13. Chromosome numbers range from 2n = 28 to 66.
The fibrous-rooted begonia (B. x semperflorens-cultorum Hort.) and the tuberous-rooted
begonia (B. x tuberhybrida Voss.) are the most important types
that are grown as bedding plants. Fibrous-rooted begonias are apparently derived
from B. cucullata var. hookeri and B. schmidtiana. Cultivars
developed from crossing these two species were released in 1878. In the middle
1800's, six tuberous-rooted Begonia species were discovered in the Andes
of South America (Bolivia, Peru): B. boliviensis, B. clarkei,
B. davisii, B. pearcei, B. rosiflora, and B. veitchii.
All except B. rosiflora are progenitors of modem cultivars of tuberous-rooted
begonia. In 1993, begonias ranked number four in the total percentage (7.5%)
of crop mix in respect to seed-propagated plants used for bedding plant production.
This translates into a gross wholesale value of approximately $49 million.
The most important types grown as potted flowering plants are the Hiemalis
begonias (B. x hiemalis Fotsch) and the Cheimantha begonia (B.
x cheimantha Everett ex C. Weber). Hiemalis begonias were developed from
crosses between B. socotrana Hook. and B. x tuberhybrida.
Cheimantha begonias were developed by crossing B. dregei Otto & A.
Dietr. with B. socotrana.
Present Germplasm Activities:
Most Begonia breeding is done in private industry. Some breeding work
is also being done at botanic gardens and by amateur hobbyists, e.g., members
of the American Begonia Society.
Status of Crop Vulnerability:
The status of indigenous populations is unknown at present. No scientific germplasm
collection trips have been taken recently, although hobbyists probably still
continue to collect material from the wild. The genetic diversity of present-day
Begonia cultivars is unknown.
Commercial Begonia cultivars are susceptible to several diseases. Hiemalis
and Cheimantha begonias exhibit varied levels of susceptibility to powdery mildew
(Erysiphe cichoracearum). Hiemalis begonias are very susceptible to bacterial
leaf spot (Xanthomonas begonias).
Most Begonia species do not lend themselves to bedding plant production
due to undesirable habit, a long cropping period, or poor seed set. Most of
these species, therefore, are relegated to hobbyist or botanical collections
and are propagated vegetatively.
Germplasm Needs:
A. Collection - Currently, GRIN lists 14 accessions at S-9 and 2 accessions
at NCRPIS for Begonia. Emphasis should be placed on collecting Begonia
germplasm from indigenous populations. Acquisition of older line-bred items
for the NPGS should be a second priority. Acquisition of F1 hybrid cultivars
should have the lowest priority. Since many botanical gardens have Begonia
collections, it would be worthwhile to obtain their inventory lists and determine
if any accessions should be acquired by the NPGS.
B. Evaluation - Each accession should be evaluated for the following traits:
growth habit and vigor; foliage size, shape, and color; time from seed sowing
to flowering; flower size and color; fertility; and resistance to Erysiphe
cichoracearum and Xanthomonas begonias.
C. Enhancement - Germplasm enhancement activities should be subordinate to
collection, evaluation, and preservation of germplasm.
D. Preservation - Emphasis should be placed on preserving seed of indigenous
species and any line-bred cultivars that can be obtained.
Recommendations:
Priority of Actions - NPGS accessions of wild species and line-bred cultivars
of Begonia should be greatly increased. Inventories of Begonia species from
botanical gardens should be obtained to determine if any accessions should be
acquired by the NPGS. All germplasm should be thoroughly evaluated for the traits
described above.
Begonia Synopsis Prepared by:
Lowell C. Ewart, Michigan State University, East Lansing, MI
CATHARANTHUS (Apocynaceae)
Introduction:
The genus Catharanthus is comprised of approximately seven species of
mostly perennial herbs. The single species in section Androyella (C. pusillus)
is native to India. All other species, contained in section Eulochnera, are
native to Madagascar. The various species, their morphological descriptions,
distributions, and putative crossing abilities are described by Veyret (1974).
The chromosome number for all Catharanthus species is 2n = 16.
Ornamental cultivars of Catharanthus are all derived from species in
the section Eulochnera. Germplasm of C. roseus and C. trichophyllus
has provided the primary material for development of ornamental cultivars. As
an ornamental, Catharanthus, more commonly known as Madagascar Periwinkle
or Vinca (not to be confused with the genus Vinca), is valued for its drought
and heat tolerance. Currently, the wholesale market value of Catharanthus
cultivars exceeds $40 million annually. Though Catharanthus cultivars
currently only account for about four percent of the total bedding plant market,
their popularity will likely increase due to their heat and drought tolerance.
In addition to its value as an herbaceous ornamental, alkaloid extracts of
Catharanthus roseus have been used in folk medicine as a diuretic,
and antidysenteric, an anti haemorrhagic and for wound healing. Folk medicine
also used extracts for treatment of diabetes. During the 1960's, as a result
of the discovery of the valuable cytotoxic alkaloids in Catharanthus roseus
(especially vinblastine and vincristine), this species became one of the major
fields of interest in modern plant cell biotechnology. During the last 30 years,
C. roseus has been used in modern medical practice as the most important
plant in treating cancer. Vinblastine sulphate is used particularly to treat
Hodgkin's disease but is also used against lymphosarcoma, choriocarcinoma, neuroblastoma
carcinoma of the breast, lungs and other organs, and in acute and chronic leukaemia.
Vincristine sulphate is used particularly to treat acute leukaemia in children
and lymphocytic leukaemia, but is also used against Hodgkins disease, Wilm's
tumor, neuroblastoma, rhabdosarcoma and reticulum sarcoma. Since these drugs
were first marketed, childhood leukaemia survival rates have increased from
IO % to 95 %. The value of alkaloids derived exclusively from C. roseus
exceeds $100 million annually.
Present Germplasm Activities:
Ornamental breeding and germplasm enhancement on Catharanthus have been
conducted by Dr. Ron Parker at the University of Connecticut. Most of the current
breeding activities are done by private companies including Goldsmith Seeds
Inc. (Gilroy, CA), PanAmerican Seed Co. (Elbum, IL), and Waller Flowerseed Co.
(Guadalupe, CA), although other flower seed companies may also have current
breeding programs. At present, there is no priority site within the NPGS for
Catharanthus. No extensive germplasm repositories are known to exist
elsewhere in the world although pharmaceutical companies may possess limited
collections.
GRIN lists 27 accessions of Catharanthus roseus. None of these
accessions are from the native range of the species. Twenty-two of the accessions
are PVP protected ornamental cultivars, whereas the remaining five accessions
are naturalized weedy ornamentals from Mexico and Guatemala. No accessions of
the other Catharanthus species are held within the NPGS.
Genetic Vulnerability:
As indicated, the native range of Catharanthus section Eulochnera
is entirely limited to Madagascar. Despite the once-rich biotic diversity of
this island, the region now stands as one of the most outstanding examples of
environmental devastation in the world. Widespread destruction of habitat and
overpopulation have undoubtedly disrupted and eliminated native Catharanthus
populations. The Missouri Botanical Garden and the Madagascar government have
undertaken efforts to preserve examples of the remaining biota. Unfortunately,
most of the protected sites lie outside the ranges of Catharanthus species.
Catharanthus ovalis, in some reports, has been listed as extinct. The
security of other species and populations is unknown. Genetic variability in
Catharanthus roseus, an especially critical species, is unknown. Because
of the very limited distribution of native populations and sensitivity of these
populations to human encroachment, the best and perhaps only way to minimize
genetic vulnerability is to collect and preserve representative wild germplasm.
Except for private germplasm collections held by seed or pharmaceutical companies,
no other germplasm repositories are known to exist. Genetic diversity in commercial
cultivars is limited primarily to backgrounds of Catharanthus roseus
and C. trichophyllus. Predominance of only a few cultivar series suggests
that genetic diversity in commercial cultivars is low.
A major shortcoming of commercial cultivars is their susceptibility to various
pathogens, especially Phytophthora. In addition, commercial cultivars exhibit
a limited flower color range. Current cultivars are adapted to warm climatic
conditions, but perform poorly in cool or wet climates.
Germplasm Needs:
A. Collection - Representative collections of all of the wild species should
be obtained as soon as possible. Delay will only result in further deterioration
of native populations and potential loss of genetic diversity. Seeds and/or
cuttings can be made in the field. Considering the limited range of many of
the species, attempt should be made to collect from ecologically diverse regions
within the range of the species.
B. Evaluation - Emphasis should be placed on collection of variability within
each species. Collections should be evaluated for horticulturally valuable traits
including novel forms, colors, habits, and disease resistance. As much as possible,
collections should be evaluated for potential use in pharmaceutical applications.
C. Enhancement - Given the vulnerability of all species to extinction, the
first priority should be directed towards mere collection of natural genetic
diversity. Beyond preservation of genetic diversity, no enhancement or modification
of the germplasm is necessary or desired. Early enhancement of the germplasm
may only serve to limit its utility in as yet unknown roles.
D. Preservation - Currently, there is no priority site within the NPGS for
Catharanthus germplasm. Therefore, a priority site needs to be established
for Catharanthus. Germplasm may be easily stored as seed for long periods
of time.
Recommendations:
Germplasm of all available species should be acquired from native populations
as soon as possible. Once acquired, the wild germplasm can be distributed for
plant improvement programs. Collections should be maintained in such a way that
horticultural traits do not have priority over potential other pharmaceutical
uses.
Researchers that may be contacted for additional information:
R.N. Bowman, Goldsmith Seeds Inc., Gilroy, CA
D.G. Holden, Waller Flowerseed Co., Guadelupe, CA
Catharanthus Synopsis Prepared By:
R.N. Bowman, Goldsmith Seeds Inc., Gilroy, CA
DENDRANTHEMA (Anthemideae; Compositae)
Introduction:
The genus Dendranthema is comprised of approximately 40 species of mostly
herbaceous (sometimes woody) perennials with corymbose inflorescences. The capitula
usually contain both disc and ray florets, but some species lack ray florets.
The center of diversity for the genus is eastern Asia, although some taxa are
found as far west as Europe. The most common chromosome numbers for the genus
are 2n = 18, 36, and 54, with x = 9. However, chromosome numbers of 2n = 42,
45, 52, 60, 70, 72, and 90 have also been reported.
By far, the most common Dendranthema taxon in cultivation is the florist's
mum [D. x grandiflorum (Ramat.) Kitam.; formerly C. x morifolium
Ramat.]. Cultivation of this hybrid-species dates back over 2,000 years. It
is used as a cutflower, potted plant, and garden subject. A 1993 survey of 36
states indicated that D. x grandiflorum was cultivated on approximately
2011 acres and had a wholesale value in excess of $176 million. Pot mums are
second only to poinsettias, whether viewed in terms of monetary value or in
units sold.
Breeding over the past 2,000 years has created and changed the wild hybrid-species
D. x grandiflorum from what it was, i.e., a two- to five-foot-tall
erect or spreading plant with small, daisy-like flowers, into the spectacular
florist's mums we have today. The National Chrysanthemum Society recognizes
thirteen classes of flower types, ranging from anemones and singles (daisy type)
to full doubles (decorative type), and with flower petals ranging from reflexed
to fully incurved. Ray petals may be flat, tubular, or combinations thereof
(spoon, spider, quilted), and in almost all colors except blue. Flower size
can vary from less than one inch to over ten inches in diameter. The chromosome
number of D. x grandiflorum is 2n = 54.
Other Dendranthema species that are often cultivated are:
Dendranthema pacifica (Nakai) Kitam. [ = Ajania Pacifica (Nakai) Bremer
& Humphries] - a low spreading perennial from the eastern coast of Japan.
The abaxial surface of the thick leaves is tomentose and silvery-white. Leaf
margins often curl, giving the appearance of a green leaf with a white or silver
border. The one-quarter inch capitula are devoid of ray petals, and appear as
clusters of little yellow buttons. Plants are often utilized as a perennial
ground cover. The species exhibits resistance to leaf miners, and has been crossed
with D. x grandiflorum in an effort to incorporate this trait
into the florist's mum. The reported chromosome number is 2n = 90.
Dendranthema indicum (L.) Des Moul. - one of the putative parents of
D. x
grandiflorum. A perennial from Japan and China with small, yellow, daisy-like
capitula in a loose corymb, growing from two to three feet tall. This species
has been utilized to develop a series of garden chrysanthemums. The reported
chromosome numbers are 2n = 36 and 54.
Dendranthema weyrichii (Maxim.) Tzvelev. - a low-growing, stoloniferous
perennial from Japan with white to pink flowers. The plant grows to perhaps
one foot tall. The chromosome number is 2n = 54.
Dendranthema zawadskii (Herbich) Tzvelev. - a two- to three-foot-tall
plant with white or pink daisy-like flowers. This species has been crossed with
D. x grandiflorum to create the Korean chrysanthemums which have
been used as garden mums. The reported chromosome numbers are 2n = 54 for D.
zawadskii var. zawadskii, and 2n = 18 for D. zawadskii
var. latilobum.
Present Germplasm Activities:
Other than some breeding research being done at the University of Minnesota,
most of the Dendranthema breeding is being done in private industry.
Very little research on Dendranthema in the United States utilizes interspecific
hybrids. However, interspecific hybrids are used in mum breeding programs in
China and Japan, where new habits and forms of mums have been created, in some
cases with resistance to adverse environmental conditions (drought, pollution,
low temperatures) or pests (insects, diseases). As always, plant breeders are
trying to develop new and novel types of plants, preferably within species that
the public has been growing for some time. We have very little idea as to what
can be obtained through interspecific hybridization within Dendranthema,
i.e., what new colors, habits, resistances, etc., can be obtained by crossing
D. x grandiflorum with other Dendranthema species, and
what new markets we can enter with these new interspecific hybrids.
Status of Crop Vulnerability:
The current status of indigenous populations of Dendranthema species
is unknown. Commercial lines and cultivars are the primary source of germplasm
for current Dendranthema breeding programs. Fortunately, Dendranthema
is primarily clonally-propagated crop and the available germplasm is (usually)
highly heterozygous. However, the germplasm base is very limited, considering
the large size of the industry.
Dendranthema x grandiflorum cultivars are host to a number of
insects and diseases, and, as a consequence, receive frequent applications of
pesticides during crop production. For worker health, environmental, and economic
reasons, it is desirable to develop cultivars that require fewer pesticide applications.
Therefore, identification of clones that exhibit resistance to diseases and/or
insects is needed for future breeding efforts. It is likely that wild species
will be the sources of pest resistance for Dendranthema breeding programs.
Germplasm Needs:
A. Collection - The NPGS currently has few Dendranthema accessions. Current
NPGS holdings include twelve clones among six taxa (D. arcticum,
D. x grandiflorum, D. indicum, D. japonicum,
D. pacificum, D. zawadskii, D. zawadskii var. latilobum),
and some seed of D. x grandiflorum. Most of the clones are at
NC-7, but the clones of D. zawadskii are at the National Arboretum. Seed of
D. x grandiflorum is held at NSSL. The current NPGS holdings of Dendranthema
represent less than 15 percent of the available species. The NPGS's Dendranthema
holdings should be increased to include seed of at least 20 representative accessions
per species, preferably obtained from several different locations within the
species' range. Each accession should consist of open-pollinated seed collected
from numerous plants at each location.
B. Evaluation - Where and when possible, multiple plants from each accession
should be evaluated for disease and insect resistance, and other attributes
including (but not limited to) growth habit and rate; size, color, and type
of capitula; and keeping quality.
C. Enhancement - Collection, evaluation, and preservation of germplasm should
receive the highest priority.
D. Preservation - see Recommendations section.
Recommendations:
Habitat destruction is occurring on every continent, often at an alarming rate,
with the simultaneous destruction of many potentially valuable species. Therefore,
it is imperative that seed of all Dendranthema species is collected in the near
future, preferably from several wild populations. Maintaining the plant materials
as seed will simplify germplasm maintenance and minimize the space required
for the collection. The accessions should be grown out and increased periodically
so that viable seed will be available for distribution to interested parties.
Researchers that may be contacted for additional information:
L.J. Glicenstein, Yoder Brothers, Inc., Salinas, CA
Dendranthema Synopsis Prepared by:
L.J. Glicenstein, Yoder Brothers, Inc., Salinas, CA
DIANTHUS (Caryophyllaceae)
Introduction:
The genus Dianthus consists of approximately 300 species of annual,
biennial, or perennial herbs that are native from Europe to western Asia and
extending south to southern Africa. Many of the species hybridize with each
other, and therefore the exact number of species is unknown. The second edition
of the International Dianthus Register contains about 27,000 entires
or names of Dianthus releases/cultivars. The chromosome numbers for Dianthus
species are n = 15, 30, and 45.
Dianthus species and hybrids are grown commercially for use as outdoor
bedding plants or for cut flowers. Plants grown for bedding outdoors include
Border Carnations, Sweet William, and Pinks. Plants grown for cut flowers include
the Glasshouse (or Florist's). Carnation and sweet william.
The Glasshouse (or Florist's) Carnation is derived mainly from D. caryophyllus
L., but also includes D. arboreus L., D. chinensis L., and D.
knappii (Pant.) Asch. & Kanitz ex Borb. in its parentage. Dianthus
caryophyllus is native to the Mediterranean region.
The Border Carnation (D. caryophyllus L.) is grown as an annual or perennial,
depending on the location and source of plant material. Border Carnations are
similar to the Florist's Carnation but the former usually have smaller flowers
and are shorter in height. The chromosome number is n = 15.
Sweet William (D. barbatus L.) is grown as a commercial cut flower and
as a bedding plant. The species is usually biennial, and is native to mountain
pastures of central and southern Europe. Plant have dark green foliage and cymose
inflorescences with densely clustered florets in shades of red, pink, salmon,
or white.
The Pinks comprise several species and interspecific hybrids of Dianthus,
and include Allwood's Pink (D. caryophyllus x D. plumarius), Alpine
Pink (D. alpinus), Cheddar Pink (D. gratianopolitanus Vill.),
China Pink (D. chinensis L.), Cottage Pink (D.plumarius L.), Deptford
Pink (D. armeria L.), and Maiden Pink (D. deltoides L.).
In the United States, the economic value of Dianthus is chiefly due
to production of the Florist's Carnation. The wholesale value of florist's carnations
produced in the United States was $64.5 million in 1985.
Present Germplasm Activities:
The number of public institutions in the United States that are conducting research
on Dianthus has declined within the past decade. Breeding research at
Colorado AES (Fort Collins) is terminating due to retirement of the principal
investigators. Limited work on cultivar development is being conducted at the
Nebraska AES (North Platte) and at several private companies. AES researchers
in Indiana (Purdue University) and California (University of California, Davis)
are studying genetic variation for postharvest quality in the Florist's Carnation.
The NPGS priority site for Dianthus is the North Central Regional Plant
Introduction Station (NCRPIS) at Ames, IA. Holdings at NCRPIS include =65 Dianthus
accessions representing 32 species, and an additional 7 accessions are maintained
at the National Seed Storage Laboratory (NSSL).
Status of Crop Vulnerability:
In most of the Mediterranean area, native populations of Dianthus are
threatened by overgrazing. A few plants can still be found on rocky outcroppings
that cannot be reached by goats. The status of indigenous populations in the
former Soviet Union is unknown. In the United States, Dianthus germplasm
is maintained by private companies, individual collectors, botanical gardens,
universities, and NCRPIS. For the most part, breeders must rely on germplasm
obtained from commercial companies or botanical gardens.
Most of the new cultivars are developed from existing commercial cultivars.
The level of genetic diversity in commercial cultivars is unknown, but is probably
significantly lower than the original parental material collected from the wild.
Several traits in Dianthus could be improved by breeding, including
pest resistance, calyx strength, stalk strength, winter hardiness, and the period
of flowering. The main disease pathogens of Dianthus are Alternaria
dianthi, Botrytis cinerea, Fusarium oxysporum f.sp. dianthi,
Phialophora cinerescens, Pseudomonas caryophylli, Uromyces
dianthi, and several viruses. The major invertebrate pests of Dianthus
are aphids, thrips, and spider mites. Hardiness and disease resistance are the
major goals for breeding Dianthus for use as garden perennials. A short
juvenility period and plant vigor are important selection criteria in breeding
Dianthus for use as annual bedding plants.
Germplasm Needs:
A. Collection - Emphasis should be placed on the following germplasm: 1) collecting
material from indigenous populations; and 2) procuring material that is maintained
in European and Asian collections. Currently, NCRPIS has 65 Dianthus
accessions, and the collection is being expanded through contacts with Indices
Seminum. Sixteen of these accessions originated from the former Soviet Union,
and the other three were obtained in Iran, Japan, and a domestic source (Colorado).
The NCRPIS collection at should be expanded to include accessions of D. caryophyllus
from southern and western Europe. Germplasm of other Dianthus species
should also be obtained, especially species that will hybridize with D. caryophyllus.
Collecting germplasm that may be resistant to disease pathogens should be a
priority.
B. Evaluation - Plant introductions should be systematically evaluated for
the following
traits: 1) compatibility of crossing with the larger-flowered D. caryophyllus
types; 2) disease resistance or tolerance; 3) duration of flowering; 4) winter
hardiness; 5) fragrance; 6) flower size and color; and 7) plant habit. Initially,
Dianthus germplasm should be maintained and evaluated in a mild winter
region until winter hardiness has been determined.
C. Enhancement - Dianthus improvement programs are mainly conducted
by private companies. Enhancement programs are needed to increase the duration
of flowering, calyx and stalk strength, disease resistance, and winter hardiness.
D. Preservation - A broad genetic base will be needed for future breeding
programs. Therefore, NCRPIS should acquire and maintain a diverse collection
of Dianthus germplasm for utilization by public and private breeding
programs. Some Dianthus germplasm will need to be maintained as asexually-propagated
clones, thus adding to the cost and complexity of preservation. Seeds of Dianthus
species and hybrids should remain viable for 15 to 20 years when stored under
cool, dry conditions.
Recommendations:
The NPGS Dianthus collection should be expanded to include germplasm
from indigenous populations and from European, Asian, and domestic collections.
Botanical gardens in China, France, Italy, Japan, Korea, Malaysia, Portugal,
Spain, and the United Kingdom should be excellent sources of Dianthus
germplasm. All accessions should be systematically screened for the horticultural
traits described above. Dianthus accessions and evaluation information
should be valuable to breeders in the public and private sectors.
Researchers that may be contacted for additional information:
J. Elsley, Wayside Gardens, Hodges, SC
D.T. Lindgren, The University of Nebraska - Lincoln, North Platte, NE
M.P. Widrlechner, USDA/ARS, NCRPIS, Ames, IA
Dianthus Synopsis Prepared by:
D.T. Lindgren, The Univeristy of Nebraska - Lincoln, North Platte, NE
DIEFFENBACHIA (Araceae)
Introduction:
The genus Dieffenbachia consists of about 30 species of erect herbs
native to tropical America. Commercially-grown Dieffenbachia rank among
the top ten ornamental tropical foliage plants in terms of wholesale dollar
value. They are prized for their attractive variegated foliage and tolerance
of interior environments.
Present Germplasm Activities:
Germplasm enhancement and breeding research on Dieffenbachia is being
conducted by the Florida AES at Apopka, Florida. Program goals include breeding
for improved plant form, novel types of foliar variegation and increased branching.
The NPGS priority site for Dieffenbachia is the National Clonal Germplasm
Repository at Miami, FL (CR-MIA). There are approximately four Dieffenbachia
accessions maintained at CR-MIA.
Status of Crop Vulnerability:
The genetic diversity within existing Dieffenbachia cultivars is difficult
to assess, because the botanical nomenclature of this genus is unclear and due
to the existence of many intra- and interspecific hybrids made in the late 1900's.
Most commercial cultivars are assigned to the species maculata or seguine, although
this may be erroneous. However, it is likely that most of the available genetic
diversity can be attributed to those two species accounting for only a small
portion of what exists in wild populations.
The most popular Dieffenbachia cultivars are propagated asexually either
via tissue culture or by tip cuttings. There are no seed propagated varieties.
Tissue culture has made production of disease- and virus-free cuttings possible
which has lessen the severity of these problems in production. Mutations arising
from tissue-culture produced populations have led to selections with improved
plant form and branching characteristics but this has not significantly increased
genetic diversity.
The major Dieffenbachia pest is spider mites. Collection of germplasm
with resistance to spider mites would be of major importance to development
of improved cultivars.
Germplasm Needs:
A. Collection - Emphasis should be placed on material collected from indigenous
populations throughout tropical America.
B. Evaluation - Plant introductions should be evaluated for resistance to
spider mites, growth habit, leaf shape and size, and degree of branching.
C. Enhancement - There is a breeding program at the Florida AES but additional
research is needed to screen Dieffenbachia accessions for mite resistance.
D. Preservation - The majority of Dieffenbachia germplasm is held by
botanic gardens or private collectors. Maintaining germplasm is difficult because
plants must be asexually propagated, they may be large in size and must be kept.
in heated and shaded greenhouses or other enclosed structure.
Recommendations:
Priority of Actions - Germplasm of Dieffenbachia species should be collected
from indigenous populations in order to expand current collections. Once collected,
material should be distributed to breeders for screening, evaluation, and utilization
in plant improvement programs.
Researchers that may be contacted for additional information:
R. J. Henny, University of Florida, Apopka, FL
Dieffenbachia Synopsis Prepared by:
R .J. Henny, University of Florida, Apopka, FL
EUSTOMA (Gentianaceae)
Introduction:
The genus Eustoma is comprised of two species. Eustoma grandiflorum
(Raf.) Shinn., commonly known as Prairie Gentian or Lisianthus, is native
from the midwestern prairies of the United States south to Mexico. Eustoma
exaltatum (L.) Griseb. is native to the southern United States, Mexico,
Central America, and the West Indies.. The two species may represent different
ecotypes of the same species, for both species are interfertile and produce
fertile progeny. In cultivation, E. grandiflorum grows like a biennial,
and first produces a rosette which bolts into a single flowering stem after
cold treatment, then dies after flowering. In contrast, E. exaltatum
grows more like a perennial in cultivation and produces additional shoots each
season. Both species have purple flowers that are funnel-shaped to , campanulate,
but corolla lobes of E. exaltatum range up to 2.5 cm in length whereas
those of E. grandiflorum are 5 to 6 cm in length. Most of the plant material
in cultivation is E. grandiflorum (2n = 2x = 36). This species is an
important seed-propagated cut flower crop in Europe and Japan. In the United
States, E. grandiflorum is just beginning to be grown, but has the potential
to become an important bedding plant, flowering potted plant, and cutflower.
Present Germplasm Activities:
Most commercial cultivars have been developed by Japanese seed companies. Several
Japanese companies have been breeding Eustoma for over 90 years, and
have released superior cultivars in a range of flower colors (pink, white and
purple) and flower forms (sprays, doubles, picotees, and bicolors). Breeding
within the United States has only recently begun. Several different dwarf cultivars
suitable as either bedding or potted plants have been released by the breeding
programs in the United States and Japan.
Sakata Seed Co., Takii Ltd., Daichi Co., Geo. Ball Co., and Dr. Brent Harbaugh
of the University of Florida have extensive collections of Eustoma species
and cultivars.
Status of Crop Vulnerability :
In North America, populations of E. grandiflorum are not common and
can be locally threatened because of habitat destruction. Eustoma grandiflorum
has been collected in Colorado, Florida, Texas and Arizona. In Mexico, populations
of E. exaltatum are more common than are E. grandiflorum populations
within the United States. Eustoma exaltatum has been collected from Florida,
California and Baja Mexico.
Most commercial cultivars have been derived from limited E. grandiflorum
germplasm that was collected in the early 1900's and improved in Japan. However,
significant genetic variation for flower color and flower shape exists within
the cultivated species. In addition, preliminary data suggest there is genetic
diversity for several isozyme alleles in cultivated germplasm of E. grandiflorum.
Germplasm Needs:
A. Collection - Emphasis should be placed on collecting seed from indigenous
populations of E. exaltatum and E. grandiflorum. Several horticulturally
important characteristics can be obtained from native germplasm. For example,
E. exaltatum collected from its southern range or low-elevation sites
can be used to incorporate heat tolerance in commercial E. grandiflorum
germplasm. Many of the superior E. grandiflorum cultivars either rosette
or produce few flowers at high temperatures. Expanded use of Eustoma
as a bedding plant requires that heat tolerant cultivars be developed. In addition,
incorporation of basal-branching and dwarf or semi-dwarf habit would enhance
the uses and acceptance of this crop. Eustoma grandiflorum germplasm
from the northern limit of its range may be useful in developing perennial cultivars.
Recommendations:
Priority of Actions - Emphasis should be placed on collecting seed of E.
exaltatum from
Mexico, Central America, and the West Indies, and collecting seed of E. grandiflorum
from
Nebraska, Kansas, and Colorado.
Researchers that may be contacted for additional information:
R. J. Griesbach, USDA, ARS, Florist and Nursery Crops Laboratory, Beltsville,
MD
Eustoma Synopsis Prepared by:
R. J. Griesbach, USDA, ARS, Florist and Nursery Crops Laboratory, Beltsville,
MD
HEMEROCALLIS (Liliaceae)
Introduction:
Hemerocallis, commonly known as daylily, is a popular herbaceous perennial.
Numerous complex hybrids are commercially available, and these hybrids are noted
for their drought and heat tolerance, winter hardiness, plant vigor and resistance
to most disease and insect pests.
Extensive hybridization has occurred during the past 100 years. Approximately
seven species were used in developing the current cultivars: H. flava
(L.) L. (= H. lilioasphodelus L.), H. thunbergii Hort. ex Bak.,
H. middendorfii Trautv. & C.A. Mey, H. minor Mill., H.
dumortieri E. Morr., H. aurantiaca Bak., and H. fulva (L.)
L.
Species are rarely used today in breeding. Hemerocallis species have
a very restricted flower color range, and are either yellow or various shades
of orange. Cultivars have been selected that express novel colors, e.g. red,
purple and pink. Species germplasm offers little for extending the range of
flower color.
Small-flowered cultivars have been obtained through breeding. These cultivars
usually produce small (5 cm) flowers on rather tall (40 cm) inflorescences.
Hemerocallis minor produces small yellow flowers and on small-leaved
plants, and this species was very important in creating these dwarf daylilies.
However, the inflorescences of H. minor are quite tall. Hemerocallis
nana W.W.Sm. & Forr. is a truly dwarf species that produce small flowers
on inflorescences that are less than 25 cm tall. This species, however, is not
in cultivation today.
Two traits have been used to prolong the flowering season. One trait that extends
the season increases the number of flowers per determinate inflorescence. In
certain cultivars, indeterminate infloresences can also be produced. A second
trait that extends the season increases the number of inflorescences. In most
cultivars and species, the infloresences develop during fall and start to elongate
during spring. In the "reblooming" cultivars, inflorescences develop
and elongate immediately as the new shoots mature. Hemerocallis multiflora
Stout could be used to extend the flowering season: this species is known to
produce up to 100 flowers per determinate inflorescence, while most Hemerocallis
species rarely produce over 20 flowers.
Present Germplasm Activities:
Almost all of the Hemerocallis breeding done today is by amateurs. Current
breeding efforts are focused on extending the flowering season, reducing plant
size, and developing new flower shapes and colors. Breeding efforts are divided
between the diploid and the tetraploid cultivars that can not be intercrossed
to produce triploids.
The NPGS priority site for Hemerocallis is the United States National
Arboretum (USNA) in Washington, D.C, and includes the following species: H.
altissima, H. aurantiaca, H. citrina, H. coreana, H.
dumortieri, H. esculenta, H. exalta, H. forrestii,
H. fulva and its many forms, H. hakurensis, H. lilioasphodelus,
H. littorea, H. middendorffii, H. minor, H. multiflora,
and 41 accessions unidentified as to species.
Status of Crop Vulnerability:
The status of indigenous populations of Hemerocallis species is unknown.
At present, commercial cultivars are the primary source of germplasm for plant
improvement programs. The level of genetic diversity in commercial cultivars
is unknown.
The genetic resources of Hemerocallis have not been fully exploited.
Only half of the known species have been used in breeding of commercial cultivars.
Germplasm Needs:
A. Collection - Several species are available in private and public collections.
The Hemerocallis collection at the USNA (Washington, D.C) contains identified
and new, unidentified species. However, the following species from mainland
China are not currently held in any collection: H. aurantiaca, H.
forrestii, and H. nana. These species contain genes for dwarfness
and anthocyanin coloration, and are needed for plant improvement programs.
B. Evaluation - All Hemerocallis accessions should be evaluated for
important horticultural traits including plant height, number of flowers per
inflorescence, length of the flowering period, cold hardiness, salt tolerance,
and disease resistance.
C. Enhancement - Useful traits in Hemerocallis species should be introgressed
into cultivated germplasm.
D. Preservation - Most species are held in collections that have sufficient
funds or interest for plant maintenance.
Recommendations:
Introgression of useful traits from Hemerocallis species into cultivated
germplasm should receive the highest priority. Amateur breeders are less likely
to accomplish this task, and therefore an ARS/AES geneticist should be responsible
for introgression. Secondly, several important Hemerocallis species (including
H. aurantiaca, H. forrestii, and H. nana) should be collected
from indigineous populations, maintained in the NPGS collection, propagated,
and made available for distribution.
Researchers that may be contacted for additional information:
J. Elsley, Wayside Gardens, Hodges, SC
HIPPEASTRUM (Amaryllidaceae)
Introduction:
The genus Hippeastrum Herbert (amaryllis) consists of approximately
60 entirely New World species (one species has naturalized in Africa). The species
are concentrated in two main areas: 1) eastern Brazil; and 2) the central southern
Andes of Peru, Bolivia and Argentina, on the eastern slopes and adjacent foothills.
Little of this genetic diversity is represented in modern amaryllis hybrids.
Hybrid strains were produced primarily from the following relatively small number
of species:
H. vittatum Herbert (Brazil, Bolivia, Peru; 2n = 22, 44): 2- to 6-flowered,
variable in form, perianth white with longitudinal red to mauve stripes on the
tepals.
H. leopoldii Dombrain (Bolivia, Peru, chromosome number unknown): 2
flowered, very wide-spreading and regular perianth, the tepals proximally bright
red with a bifid white keel in the lower half, apically white.
H. pardinum (Hook. f.) Lemaire (Bolivia, 2n = 22): 2-flowered, tepals
with greenish background, suffused and densely spotted with red.
H. reginae Herbert (Mexico to Bolivia, 2n = 33, 44): 2- to 4-flowered,
perianth red with whitish green keels and throat.
H. puniceum (Lamarck) Kuntze (Mexico through South America including
the West Indies, 2n = 22, 33): 2-4 flowered, perianth salmon, orange, white,
pink or red and yellowish-green in the throat.
H. aulicum Herbert (Brazil to Paraguay, 2n = 22): frequently epiphytic,
flowers 2, perianth bright crimson, green at the base.
Present Germplasm Activities:
A breeding program emphasizing Brazilian diploid amaryllis species not currently
represented in modern cultivars has been underway at the University of Florida's
Fort Lauderdale Research and Education Center since 1988. Objectives are to
develop evergreen cultivars with attractive foliage and fragrant flowers of
novel floral form and coloration patterns with resistance to hippeastrum mosaic
virus and red scorch (Stagonsopora curtisii). A breeding program focusing
primarily on Andean species is conducted in Escondido, California under the
aegis of Fred Meyer, a commercial floriculturist and plant breeder. Collection,
evaluation and preservation of Hippeastrum germplasm are conducted as
part of both programs. Two breeding programs focusing on hybrid material exclusively
are located in Bradenton, Florida (University of Florida Gulf Coast REC) and
Gainesville (Amaryllis Bulb Company, a commercial firm). A breeding program
of unknown scope is also underway at Oklahoma State University. Many amateur
breeders around the country are also involved in hybridizing amaryllis. The
NPGS priority site for Hippeastrum is CR-MIA (Miami, FL). There are approximately
11 Hippeastrum accessions maintained at CR-MIA.
Status of Crop Vulnerability:
Commercial breeding efforts subsequent to the initial flurry of primary hybridization
in amaryllis has largely been concentrated among the hybrids themselves. Thus,
there has never been any attempt by breeders to accumulate and maintain a broadly-based
germplasm collection of wild species. The overwhelming majority of Hippeastrum
species are diploid, with somatic chromosome number of 2n = 22. Virtually all
of the complex hybrid material presently in cultivation is tetraploid, a result
of both selection for tetraploid progeny (often associated with plant and flower
size increases in hybrid amaryllis) and incorporation of a few natural tetraploid
species in early hybridization efforts. It is thus evident that little more
than 10% of the genomic diversity of Hippeastrum is represented within
commercial cultivars. Even among breeders using wild-collected species in their
breeding programs, most of the germplasm can be traced to a single (often undocumented)
collection which has then been propagated vegetatively or by seed. The most
obvious means to reduce or minimize the genetic vulnerability of commercial
amaryllis is the expansion of the gene pool currently represented in cultivars.
Although many new species of Hippeastrum have been described in the
last 30 years, it is evident from recent systematic approaches to the genus
that many of these new taxa represent only variants of more widely-ranging species.
It is thus difficult to compose a highly accurate estimate of the vulnerability
of wild populations. Habitat destruction is without a doubt the most serious
threat to wild amaryllis populations, especially species that occur within or
at the margins of tropical forest ecosystems (probably about 50% of currently
known species). The coastal rain forest of Brazil, for example, has been reduced
to 2% of its original extent, and forest-dwelling amaryllis species such H.
reticulatum Herbert have no doubt suffered losses. Nonetheless, it is still
possible to find populations of this species in residual forest communities
in eastern Brazil. Of the six important amaryllis species listed above, H.
pardinum, and, until recently, H. leopoldii, were known only from
their original collections. H. brasilianum (Traub & Doran) Ravenna,
an important component of the Fort Lauderdale breeding program, is currently
known only from cultivation in Brazil.
Hippeastrum mosaic virus is probably the greatest limitation on expansion
of amaryllis production in the United States. There has never been any attempt
to assess degree of resistance among amaryllis species. Hippeastrum papilio
(Ravenna) Ravenna does not manifest mosaic symptoms, and thus has been an important
component species for the Fort Lauderdale breeding program. Hybrids of this
species show considerable variation in their expression of visual mosaic symptoms.
Thus breeding for resistance to this virus and, secondarily, to the fungus Stagonospora
curtisii are useful directions for any breeding program with amaryllis.
On other fronts, the species H. blossfeldiae occurs along the coast in
Brazil where it receives direct salt spray, suggesting that it might impart
salt tolerance to its hybrids.
Germplasm Needs:
A. Collection - While it would be beneficial to place emphasis on new collections
of amaryllis species from indigenous populations, the social and political problems
occurring in a number of nations where amaryllis species are most widely represented
present great obstacles to success. Such collections need to proceed with sensitivity
to the sovereignty of those countries, and preferably in cooperation with scientists
within those countries. It is imperative that each wild population be sampled
adequately, because most diploid Hippeastrum species exhibit self-incompatibility.
Peruvian and Bolivian amaryllis should be a particular focus for collection
because they appear to be the least well known. There should also be a sustained
attempt to access domestic holdings of amaryllis species collections through
a central data base.
B. Evaluation - Amaryllis introductions should be assayed for resistance to
hippeastrum mosaic virus and Stagnospora red scorch. Ploidy level of new collections
should be determined. New introductions should also be evaluated for flower
number, foliage quality (including persistence), and for any attributes of floral
morphology that could be considered novel and exploitable for breeding efforts.
C. Enhancement - Breeding programs are underway at the University of Florida,
Oklahoma State University, and by both amateur and commercial interests. Enhancement
need not be a priority at the NPGS site(s) unless it coincides with breeding
programs in progress at the same location(s).
D. Preservation - A sizable species collection (=20 spp.) is maintained at
the University of Florida-IFAS Fort Lauderdale REC. A large collection (= 30-40
spp.) is also under the private ownership of Fred Meyer in Escondido, California.
A number of amateur breeders around the country maintain small species collections;
the best collections of these type are located in California. Additional germplasm
collections are present in Argentina, Brazil, Chile and Peru, though the exact
status of their condition is not well known.
Recommendations:
A program should be initiated to access collections currently in the United
States, whether in the possession of botanical gardens, university departments,
commercial firms or private collectors. It should be requested that seed or
offset bulbs of these collections be deposited at the NPGS priority site (CR-MIA).
Virused accessions will need to be micropropagated using documented protocols
for virus elimination. Secondly, NPGS should support a program of collection
of new Hippeastrum germplasm from Latin America. Research on long-term
storage of amaryllis seed needs to be undertaken as well, since most amaryllis
bulb collections eventually contract mosaic virus in cultivation.
Researchers that may be contacted for additional information:
A.W. Meerow, University of Florida, Fort Lauderdale, FL
Hippeastrum Synopsis Prepared by:
A.W. Meerow, University of Florida, Fort Lauderdale, FL
IMPATIENS (Balsaminaceae)
Introduction:
Impatiens is an exceedingly large and complex genus, and is comprised
of 600 to 1000 species of annual or perennial herbs or subshrubs. They are mainly
distributed in the tropics and subtropics of Asia and Africa, with a few species
native to the temperate regions of China, Europe, and North America. Three separate
centers of diversity have been proposed: 1) the Himalayas, which gave rise to
the temperate species (x = 7, 9, 10); 2) southern India and Sri Lanka, which
gave rise to the African species (mostly x = 8); and 3) southeast Asia, and
extending to Indonesia and New Guinea (mostly x = 7).
Impatiens wallerana Hook. f. (formerly I. sultanii sultana Hook.
f.) is native from Tanzania to Mozambique and is found in damp, often shaded
locations from sea level to 1800m (n = 16). It is the most widely cultivated
species in the genus and is believed to be the second most economically-important
flowering plant in the United States. The farm gate value for impatiens sold
in the United states is roughly estimated at $200 to $250 million in 1992. Most
cultivars of I. wallerana are seed-propagated.
Also horticulturally important are the New Guinea impatiens, hybrids involving
I. aurantiaca Teysm., I. hawkeri Bull., and possibly other species
(2n = 4x = 28). Plants are used as flowering pot plants indoors or for bedding
outdoors. Most cultivars are propagated by shoot-tip cuttings. The wholesale
value of New Guinea impatiens is approximately $12 million annually.
Of lesser importance are I. balsamina L. (balsam impatiens), an artificial
hexaploid hybrid of I. platypetala Lindl. x I. hawkeri (sold commercially as
'Tango' and 'Tangeglow'), I. niamniamensis Gilg., I. repens Moon,
and I. sodeni Engl. & Warb.
Present Germplasm Activities:
A small species collection is maintained at the Connecticut AES (Storrs), and
interspecific hybridization research was carried on there at least until the
mid- 1980s. It is not known whether this program is still active. A fairly extensive
collection is maintained at Kew Gardens (Richmond, United Kingdom).
In the United States, breeding programs for I. wallerana are conducted
by PanAmerican Seed Company (Elbum, IL), Goldsmith Seeds, Inc. (Gilroy, CA),
and Bodger Seed Company (Lompoc, CA). Several foreign seed companies also have
breeding programs on I. wallerana. Breeding of New Guinea impatiens is
being carried out by Ball Floraplant (G.J. Ball Company, Nipomo, CA), PanAmerican
Seed Company (Elbum, IL), Mikkelsen's, Inc. (Ashtabula, OH), and Iowa State
University (Ames, IA).
The NPGS priority site for Impatiens is CR-MIA (Miami, FL). At present, there
are 5 Impatiens accessions at NCRPIS, 1 at NPMC, 23 at Glenn Dale, and
5 at NSSL.
Status of Crop Vulnerability:
Although we have no specific knowledge concerning the status of wild Impatiens
populations, we can assume that ecological destruction in tropical Africa, the
Himalayas, Sri Lanka, and southeast Asia is diminishing the habitat for many
species. Many of the tropical species are highly endemic, and these species
should receive high priority for collection due to their genetic vulnerability.
The few temperate species are far more widespread and should not require collection
at this time.
Wild populations of I. wallerana are very heterogeneous, and natural
hybrids between I. wallerana and I. usambarensis are observed
in the wild. Impatiens cinnabarine may also be genetically compatible
with I. wallerana. The size of the original I. wallerana collection
is not known, and it is also not known if other accessions were added to the
original collection since breeding work began in the 1940s. A wild I. wallerana
seedling collected in the early 1950s from a naturalized population in Costa
Rica conferred genes for dwarf growth habit, flower color, and pigment patterning
(including the "eyed" and "blush" types). Intercrossing
and selection have generated a vast amount of genetic variation for plant height,
flower color, flower size, time of flowering, and several other traits.
Impatiens species may be able to contribute useful traits to I. wallerana.
Impatiens usambarensis is reported to grow in more exposed, sunny habitats than
I. wallerana, and therefore might be expected to confer genes for sun
tolerance. Flower color in I. wallerana is controlled by several modifying
and intensifying alleles, and the flower color range may be extended in this
species by hybridization with I. usambarensis. Yellow flower color does
not exist in I. wallerana, but several other Impatiens species
have yellow flowers, including I. auricoma Baill. Primary hybrids between
I. wallerana and I. auricoma have been obtained.
Germplasm Needs:
A. Collection - Germplasm needs to be collected from wild populations for
several Impatiens species. Impatiens wallerana, I. usambarensis,
and their natural hybrids need to be collected from Tanzania, Mozambique, Malawi,
and other African countries. Additional germplasm of I. auricoma and
similar species may include individuals that are more genetically cross compatible
with I. wallerana, increasing the probability of introgressing yellow
flower color into the commercial cultivars. Alternatively, a diverse collection
of species germplasm may provide material for the domestication of new Impatiens
crops with unique characteristics. Possibilities include different flower forms
(ex. - I. nzoana from Ivory Coast or I. tincoria from Kenya),
an extended color range (ex. - flower color in an unidentified Impatiens
species from Madagascar ranges from yellow to rose and purple), novel plant
habits (ex. - the rhizomatous species I. Serpens from Tanzania has a
prostrate growth habit), and frost hardiness (ex. - the tuberous species I.
cinnibatina from Tanzania). Most of the desirable traits are found in the
African Impatiens species. Detailed information is found in the book,
'Impatiens of Africa,' by Christopher Grey-Wilson, A.A., Balkema, Rotterdam
(1980).
Several of the Himalayan Impatiens species exhibit interesting traits
and should be collected. The Nepalese species I. decipiens, for example,
has metallic blue flowers. Some of the Himalayan species have been collected
by the G.J. Ball Company in conjunction with the Royal Botanic Gardens at Kew
and Edinburgh. This collection is still under study, but the species generally
have proven less amenable to cultivation that the African species. Typically,
the seeds require stratification for germination and the plants are slow growing,
non-vigorous, and sparse in flowering.
The 1970 expedition by the USDA and Longwood Gardens (Kennett Square, PA)
to New Guinea resulted in the collection of several Impatiens species.
Over the past two decades, this germplasm has been transformed into a major
floricultural crop: the New Guinea impatiens. Detailed records of this expedition
should be studied to determine the breadth and depth of this original effort
and whether a follow-up expedition is required for germplasm collection.
B. Evaluation and Enhancement - Because of the commercial importance of this
genus, private companies will be willing to cooperate with USDA/AES scientists
in the evaluation and enhancement of Impatiens germplasm. Chromosome counts
for accessions, studies of interspecific hybridization, and colchicine treatment
of primary hybrids are activities that could be performed by USDA/AES scientists.
C. Preservation - Most Impatiens species are protandrous and highly
outcrossed, and therefore plant introductions require isolation during seed
production in order to maintain purity. Generally, Impatiens seeds are
short-lived. Seeds begin to lose vigor within two years even under ideal storage
conditions, and seldom retain viability longer than four years. Ideally, germplasm
should be maintained vegetatively in a clean, well-managed greenhouse or in
vitro. At this time, virtually all existing Impatiens germplasm in
the United States is maintained by private companies.
Recommendations:
The first priority is collection of Impatiens species from central tropical
Africa and Madagascar. The second priority should be the procurement of germplasm
from Kew Gardens. The Kew gardens germplasm should serve to complement and broaden
(but not duplicate) the African collection. The involvement of the acknowledged
Impatiens expert, Christopher Grey-Wilson (currently editor of the Alpine
Garden Society Magazine), should be sought for collecting germplasm in Africa.
An adequate site needs to be designated within the NPGS for the Impatiens collection.
The collection should not be located in a hot, dry climate. Due to the susceptibility
of Impatiens to several viruses (TSWV, TMV, TRSV, CMV, etc.), the collection
should be maintained in a facility that minimizes the possibility of virus infection
by excluding virus vectors. Tissue culture facilities may be valuable for plant
maintenance and embryo rescue.
Finally, a cytogeneticist will be required to perform chromosome counts and
crossability studies on the collected germplasm.
Researchers that may be contacted for additional information:
E. Leue, PanAmerican Seed Co., Elbum, IL
Impatiens Synopsis Prepared by:
E. Leue, PanAmerican Seed Co., Elbum, IL
LIATRIS (Asteraceae)
Introduction:
The genus Liatris consists of approximately 32 species of perennial
herbs with erect, leafy, usually slender stems that terminate in a spicate or
racemose inflorescence. The genus is indigenous to North America, with species
occurring in almost every state of the Union east of the Rocky Mountains, and
extending into southern Canada and northern Mexico. The center of genetic diversity
for Liatris is the United States.
Liatris is comprised of a taxonomically complex group of species. Most
of the diagnostic characters of the species are to be found in the capitula,
including the characteristics of the phyllaries, number of florets per capitulum,
presence or absence of pubescence inside the corolla tube, and degree of plumosity
of the pappus hairs. The perennating structure is usually a globose or ovoid
corm, although some species produce a rhizome or elongated root crown.,
At least 13 species, together with several interspecific hybrids and botanical
varieties, have been introduced into cultivation and are grown commercially
as garden plants and/or cut flowers. The three most common species in cultivation
are L. aspera Michx., L. pycnostachya Michx., and L. spicata
(L.) Willd.
Liatris aspera is a perennial herb with erect, stiff stems, 40-110 cm
in height, and linear to linear-lanceolate leaves. The sessile capitula contain
25-40 florets with purple corollas. It is native from southwestern Ontario to
Minnesota and south to Florida and Texas, and inhabits dry, sandy soils of dunes,
fields, abandoned roads, and railroad embankments. The natural flowering period
for L. aspera is August.
Liatris pycnostachya is a coarse perennial herb with erect, stiff stems,
60-150 cm in height, and linear leaves. The sessile capitula contain 5-12 florets
with purple, rose-purple, or white corollas. The species is not readily distinguished
from L. spicata, except by its recurving, acuminate rather than appressed,
obtuse phyllaries. It is native from Indiana to South Dakota and south to Florida,
Louisiana, and Texas, and typically inhabits damp meadows and tall grass prairie.
The natural flowering period is during August and September.
Liatris spicata is the most commonly cultivated species, and has recently
become an important commercial cut flower. Stems are erect and stiff, 60-150
cm in height, with linear leaves. The inflorescence is a dense cymose spike
composed of sessile or peduncled capitula with 4-18 florets. The corolla is
purple, rose-purple, or white. It is distributed from Long Island to Michigan,
south to Florida and Louisiana, and is endemic to marshy places and damp meadows.
The natural flowering period is July through September.
Liatris spicata is a common garden perennial and is gaining steadily
in importance as a commercial cut flower. In commercial practice, Liatris
is propagated by seed or corm division. Commercial growers of L. spicata
prefer 1-year-old corms for cut flower production. Most L. spicata cultivars
are raised from seed by specialist corm producers, who then sell the 1-year-old
corms for flowering in the following year. Plants sold under the name 'Callilepsis'
(also listed as L. callilepis or L. callilepsis) are L. spicata
selections that are propagated exclusively by corm division. Crops of 'Callilepsis'
are generally more uniform than crops from seed-propagated corms. In addition,
the greatest market demand for cut Liatris is for stem lengths greater
than 80 cm; 'Callilepsis' is the best cultivar for producing long stems. However,
the rate of increase from corm division is slow; as a consequence, 'Callilepsis'
corms cost about 2/2 times more than seed-propagated corms.
Production difficulties include poor and/or slow seed germination, nonuniformity
of stem length and flowering time among seed-propagated cultivars, disease susceptibility,
and sporadic flowering during the first season from a mid-winter sowing. Improvements
in seed germination, disease resistance, and crop uniformity are thus needed.
Limited information has been published on breeding and genetics of Liatris.
The haploid chromosome number for the genus is 10, and the following species
are diploids (2n = 20): L. acidota, L. aspera, L. cylindracea,
L. graminifolia, L. Helleri, L. punctata, L. pycnostachya,
L. scariosa, L. spicata, and L. squarrosa. For L. punctata,
2n .= 40 has also been reported.
Present Germplasm Activities:
Breeding research on Liatris is currently being conducted by the Massachusetts
AES at Amherst, MA and the Wisconsin AES at Madison, WI. The goals of the Massachusets
AES program include improved seed germination and early flowering. The goals
of the Wisconsin AES include short-stature cultivars for potted plant production
and improved disease resistance. The NPGS priority sites for Liatris are Western
Regional Plant Introduction Station (WRPIS) at Pullman, WA and CR-MIA (Miami,
FL). Activities at WRPIS include collection and preservation of germplasm as
seed samples. A few plant accessions are maintained at CR-MIA.
Status of Crop Vulnerability:
Three Liatris species are listed (or are candidates for listing) on
the Federal Endangered Species List: L. helleri, L. ohlingerae,
and L. provincialism The status of indigenous populations of other Liatris
species is unknown. At the present time, commercial cultivars are the primary
source of germplasm for plant improvement programs. The level of genetic diversity
in commercial cultivars is unknown. The genetic resources of this genus has
yet to be fully exploited.
In the United States, L. spicata is subject to several diseases, including
leaf spots (Phyllosticta liatridis and Septoria liatridis), rusts
(Coleosporium laciniariae and Puccinia liatridis), stem rot (Sclerotinia
sclerotiorum), powdery mildew (Erysiphe cichoracearum), and wilt
(Verticillium albo-atrum). Commercial cultivars of L. spicata
are either highly susceptible or exhibit limited resistance to these pathogens.
Incorporation of genes conferring resistance into commercial cultivars would
be valuable to the industry.
Germplasm Needs:
A. Collection - Emphasis should be placed on material collected from indigenous
populations. Currently, WRPIS has 5 seed accessions of L. punctata and
the CR-MIA (Miami, FL) has 2 live plant accessions ( 1 L. tenuifolia
and 1 unknown Liatris species). The Soil Conservation Service (NPMC)
has seed accessions of L. pycnostachya and L. scariosa. The NPGS
holdings should be expanded significantly to include approximately 20 accessions
of each Liatris species that is not on Federal Endangered Species List,
and approximately 50 accessions for the economically important species, i.e.,
L. aspera, L. pycnostachya, and L. spicata.
Sources of resistance to the pathogens described previously are needed in
L. spicata. Novel growth habits, flower forms, and flower colors are
needed in L. spicata.
B. Evaluation - Plant introductions should be systematically screened for
disease resistance and evaluated for the following characters: % seed germination,
plant height, stem stiffness, florets per capitulum, and corolla color.
C. Enhancement - At present, there are breeding programs at the Massachusetts
AES, the Wisconsin AES, and private seed companies. However, more research is
needed to screen accessions for sources of disease resistance. Germplasm enhancement
activities at the NPGS priority sites for Liatris (WRPIS and CR-MIA)
should be subordinate to collection, evaluation, and preservation of germplasm.
D. Preservation - The majority of the Liatris germplasm used in domestic
improvement programs is maintained by private seed companies. Within the NPGS,
emphasis should be placed on developing and maintaining populations that are
representative of the germplasm of an area rather on single plant collections.
Liatris is an entomophilous genus that is pollinated by Lepidoptera and
Hymenoptera. Experiments involving the bagging of individual capitula and entire
inflorescences have revealed the presence of self-incompatibility (SI) in L.
aspera, L. pycnostachya, and L. spicata; SI has also been
documented in L. scariosa. Plant introductions thus require isolation
during seed production in order to maintain purity, and several SI genotypes
are needed for intercrossing within Pls.
Recommendations:
Priority of Actions - Germplasm of the important Liatris species (L.
aspera, L. pycnostachya, and L. spicata) needs to be collected
from indigenous populations in order to preserve the wild material for plant
improvement programs. Secondly, the NPGS holdings should be expanded to include
accessions of each Liatris species that is not under cultivation. The
collected material needs to be thoroughly evaluated in replicated trials for
horticultural traits.
Researchers that may be contacted for additional information:
T.H. Boyle, University of Massachusetts, Amherst, MA
D.P. Stimart, University of Wisconsin, Madison, WI
Liatris Synopsis Prepared by:
T.H. Boyle, University of Massachusetts, Amherst, MA
LILIUM (Liliaceae)
Introduction:
The genus Lilium consists of about 70 species which are found in the
temperate and subtropical zones of the northern hemisphere. The species occur
in a broad band across North America and from Spain eastward to Kamchatka and
the Philippines. The genus is divided into the following seven sections: 1)
Martagon; 2) American; 3) Candidum; 4) Oriental; 5) Asiatic; 6) Trumpet; and
7) Dauricum. Some of the sections are partitioned into subdivisions.
Plants are long-lived perennials with scaly bulbs, stolons or rhizomes. Stems
are upright and unbranched, with alternate or whorled leaves. The funnelform,
cup-shaped or campanulate flowers are solitary and terminal in racemes, panicles
or umbels. Flower color ranges from white to yellow, orange, red, purple or
maroon.
Lilium species are endemic to a wide range of edaphic conditions which
include bogs, calcareous soils, and dry, hard, stony soils. They grow in full
sun to heavy shade. Some Lilium species are distributed widely, e.g.,
L. martagon spans Europe and L. philadelphicum covers the North
American continent. Others are confined to small isolated areas, e.g., L.
macklinae which grows on one mountain in Burma and L. pitkinense
which is found in one bog in California.
Propagation of many species is often slow to difficult. Thus, ornamental characteristics
of many species have not been introgressed into commercial cultivars. Habitat
destruction and a long regeneration period threaten many species.
The ornamental value of lilies as potted plants, cut flowers, and garden plants
is recognized worldwide. The food and medicinal value of some species is documented,
but poorly studied. Wholesale value of lilies remains undetermined, but is estimated
at about $61 million annually. Lilies of the greatest ornamental value are derived
from species in the Asiatic, Oriental, and Trumpet sections. Species of the
remaining four sections have ornamental value, but have been inadequately studied
due to rarity, specific growth requirements, and/or propagation difficulties.
Present Germplasm Activities:
In the United States, breeding and germplasm enhancement of lilies is being
conducted by members of the lily societies and by private companies in the Pacific
Northwest and southeastern Minnesota. The NPGS priority site for Lilium
is NCRPIS (Ames, IA). The NCRPIS Lilium collection consists of 11 accessions,
including L. carniolicum, L. cordatum, L. distichum, L.
leucanthum, L. martagon, L. philippinense, and L. tenuifolium.
Two additional Lilium accessions are held at USNA.
Status of Crop Vulnerability:
The status of indigenous Lilium populations is unknown. However, many
of the American species (approximately 20) are located in small isolated areas.
These areas are threatened and many are being destroyed. At the present time,
commercial cultivars are the primary source of germplasm for plant improvement
programs. Gametophytic and unilateral incompatibilities can restrict genetic
recombination. Most cultivars are diploid (n = 12), although a few tetraploids
(n = 24) have been developed. Several disease-causing organisms and invertebrate
pests have been reported to attack Lilium species and cultivars. Disease-causing
organisms include Botrytis, Cercospora, Cercosporella, Cladosporium, Colletotrichum,
Corynebacterium, Cylindrocarpon, Fusariwn, Erwinia, Heterosporium, Macrophomina,
Penicillium, Phytophthora, Pseudomonas, Puccinia, Pythium, Ramularia, Rhizoctonia,
Rhizopus, Sclerotium, and Uromyces. Many viruses and virus complexes
incite severe epiphytotics. Invertebrate pests include insects, nematodes, mites
(Rhizoglyphus), and slugs (Lamix). Insects of concern include
Acyathosiphon, Aphis, Apocelus, Bradysia, Chysomphalus, Ctenothrips, Cumeues,
Diabrothica, Emboloecia, Franklinella, Hercenothtips, Lilioceris, Lithrops,
Macrosiphum, Myzus, Neolasioptera, Neomyzus, Papaimema, and Scutigerella.
Nematodes of concern include Aphelenchoides, Meloidogyne, and Pratylenchus.
Identification of sources of resistance or tolerance to pests or disease-causing
organisms is needed.
Germplasm Needs:
A. Collection - Emphasis must be placed on collecting material from indigenous
populations. Currently, the NPGS Lilium collection at NCRPIS has 11 accessions.
The NPGS holdings should be expanded significantly to include the five species
of the Martagon section, the 21 species of the American section, the eight species
of the Candidum section, the six species of the Trumpet section, and the single
species of the Dauricum section. The NPGS collection should also maintain a
collection of older cultivars that are in danger of being permanently lost.
B. Evaluation - Plant introductions should be screened systematically for
resistance or tolerance to pests or disease-causing organisms. Accessions should
be evaluated for: plant height and habit; leaf form; and flower form, orientation,
and color. Systematic evaluation of species and cultivars is needed since previous
evaluations (executed by members of lily societies) have not been thorough.
C. Preservation - In the United States, the majority of Lilium germplasm
used for breeding is maintained by amateur breeders. A comprehensive collection
consisting of multiple accessions per species needs to be developed within the
NPGS.
Recommendations:
Priority of actions - Due to deterioration of specialized habitats, collection
of as many species as possible must be done to preserve the remaining wild material.
Emphasis should be placed on collecting Lilium species which are progenitors
of the commercial cultivars, i.e., those within the Asiatic, Oriental, and Trumpet
sections. Collected germplasm needs to be evaluated in replicated trials for
ornamental, medicinal, and culinary value. Accessions with horticultural merit
need to be propagated and made available for plant improvement programs.
Researchers that may be contacted for additional information:
J. Elsley, Wayside Gardens, Hodges, SC
D.P. Stimart, University of Wisconsin, Madison, WI
M.P. Widrlechner, NCRPIS, Ames, IA
Lilium Synopsis Prepared by:
D.P. Stimart, University of Wisconsin, Madison, WI
LOBELIA (Lobeliaceae)
Introduction:
Lobelia is a large genus consisting of approximately 375 herbs, shrubs
and trees. Plants are native mostly to tropical and warm-temperate regions.
Of most interest to the cut flower and bedding plant industries are the herbaceous
annual and perennial species.
The following Lobelia species are most commonly grown:
Lobelia cardinalis L. (Cardinal Flower) is a perennial herb that grows
to 100 cm in height. The scarlet, pink, or white flowers are 3 to 4 cm long.
This species is commonly grown as a garden perennial and is also useful for
cut flowers. It is native from New Brunswick to Minnesota, and south to Florida
and east Texas. The chromosome number is 2n = 14.
Lobelia erinus L. (Edging Lobelia) is an annual or perennial
herb growing mostly less than 20 cm in height. The species is native to South
Africa and is used as a bedding plant. Flowers are about 1 cm long and come
in various shades of blue, pink, and lilac, and also in white. Chromosome numbers
are 2n = 28 or 42. Lobelia erinus is the most economically-important
Lobelia species in the flower seed business.
Lobelia siphilitica L. (Blue Cardinal Flower) is a perennial herb that
grows to 100 cm in height. The blue or white flowers are about 2 cm long. This
species is native from Maine to South Dakota, and south to North Carolina, Mississippi,
and Kansas. The chromosome number is 2n = 14. Lobelia siphilitica has
been crossed with L. cardinalis (= L. x gerardii Chabanne &
Goujonex Sauv.).
Lobelia splendens Willd. (= L. fulgens) is a perennial herb similar
to L. cardinalis that is native to Mexico.
Lobelia tenuior R. Br. is an annual species to 60 cm in height, with
flowers that are about 2 cm long. It is native to Australia and is occasionally
grown as a potted plant. The chromosome number is 2n = 18.
Present Germplasm Activities:
Most of the breeding in recent times has been carried out by commercial seed
companies using primarily L. cardinalis, L. erinus, and L.
siphilitica. At present, there is no priority site within the NPGS for Lobelia.
There are no Lobelia accessions listed in GRIN at the present time.
Status of Crop Vulnerability :
There is no current information on the status of L. erinus in South
Africa or for L. tenuior in Australia. Additional investigation is needed
to assess the vulnerability of indigenous populations for these two species.
The two American species, L. cardinalis and L. siphilitica, are
widespread in their native habitats and do not appear to be threatened.
Germplasm Needs:
A. Collection - Emphasis should be placed on collecting material from indigenous
populations in South Africa, Australia, and North America. Considering the vast
number of Lobelia species that have been discovered, it should be possible
to find additional species that may be worthy of cultivation and/or useful in
breeding.
B. Evaluation - Plant introductions should be screened in a cool climate region.
However, it would be very useful to discover some heat-tolerant species or biotypes.
C. Enhancement - Plant introductions should be systematically screened for
traits of horticultural interest, including mature plant height, branching,
days to flowering, flower color, and heat tolerance. It is probable that most
of the germplasm enhancement will be done by the private sector, but it would
be desirable for one of the AES or PI stations to develop a small project with
Lobelia.
D. Preservation - Lobelia is strongly cross pollinated, and therefore
accessions will need to be isolated during flowering in order to maintain seed
purity.
Recommendations:
Germplasm of commercially-important and new species needs to be collected,
evaluated at various locations, and maintained at a location that meets the
environmental requirements for the species. Lobelia is becoming a more
important floricultural crop, both in the flower seed business and in cut flower
markets. The estimated annual seed sales for Lobelia worldwide is approximately
2 million dollars (wholesale).
Researchers that may be contacted for additional information:
D.G. Holden, Waller Flowerseed Co., Guadalupe, CA
D.G. Lemon, Oglevee Ltd., ConnellsviBe, PA
Lobelia Synopsis Prepared by:
D.G. Lemon, Oglevee Ltd., Connellsville, PA
PELARGONIUM (Geraniaceae)
Introduction:
The genus Pelargonium consists of approximately 250 species of subshrubs,
herbaceous perennials, and annuals. The center of diversity of the genus is
South Africa, but a few species are found in tropical Africa, eastern Asia,
and Australia.
The most important types that are grown as floricultural crops are the Zonal
Geranium (P. x hortorum L.H. Bailey), Ivy Geranium [P. peltatum
(L.) L'Herit.], and Regal Pelargonium (P. x domesticum
L.H. Bailey). The Zonal Geranium is a complex group of hybrids derived from
crosses between P. inquinans (L.) L'Herit. and P. zonate (L.)
L'Herit. Zonal Geranium and Ivy Geranium are used extensively as bedding plants,
and their wholesale value in the United States was about $157 million in 1993.
Regal Pelargoniums have a complex ancestry, and are probably dervived
from P. cucullatum (L.) L'Herit., P. fulgidum (L.) L'Herit., P.
grandiflorum (Andrews) Willd., and other species. Regals are used primarily
as a potted flowering plant.
Present Germplasm Activities:
Most of the breeding of this crop is being done by private companies, including
Ball FloraPlant (West Chicago, IL and Nipomo, CA), Goldsmith Seed Co. (Gilroy,
CA), and Oglevee Ltd. (Connellsville, PA and Lompoc, CA). The Pennsylvania State
University (University Park, PA) has been active in Pelargonium breeding
for many years. Several universities perform evaluation trials of commercial
cultivars.
Status of Crop Vulnerability:
Indigenous populations of most Pelargonium species appear to be well
protected in South Africa. The level of genetic diversity in cultivated Pelargonium
germplasm is unknown.
Commercial cultivars of Pelargonium exhibit several shortcomings. More
heat tolerance needs to be incorporated into the Ivy Geranium and Regal Pelargonium.
Resistance to major pests needs to be incorporated, e.g., whitefly resistance
in the Regal Pelargonium and tobacco budworm resistance in the Zonal
Geranium. Many Pelargonium species are not suited for use as floricultural
crops and are grown by hobbyists.
Germplasm Needs:
A. Collection - Collection of Pelargonium germplasm from wild populations
is not a high priority. Presently, extensive collections of Pelargonium
species are maintained at the National Botanic Gardens of South Africa (Kirstenbosch)
and University of Stellenbosch. There is also a small collection of species
at the University of California (Irvine campus) and Cornell University (Ithaca,
NY). However, it is desirable to have seed accessions of Pelargonium
species within the NPGS, and especially those species that are progenitors of
the Zonal Geranium, Ivy Geranium, and Regal Pelargonium.
B. Evaluation - Breeders need to incorporate more heat, disease, and insect
resistance into cultivated material. Therefore, screening accessions for heat
and pest resistance would be valuable. Research on flower color transformation
would also be of value.
C. Enhancement - Enhancement of Pelargonium germplasm by NPGS personnel is
a low priority activity.
D. Preservation - Seeds of Pelargonium species need to be preserved within
the NPGS.
Recommendations:
Priority of Actions - Acquire seeds of Pelargonium species that are
the progenitors of the Zonal Geranium, Ivy Geranium, and Regal Pelargonium,
and evaluate the accessions for heat and pest resistance. Germplasm exhibiting
novel traits and/or pest resistance should be increased and made available to
breeders.
Researchers that may be contacted for additional information:
D.G. Lemon, Oglevee Ltd., Connellsville, PA
R.Craig, The Pennsylvania State University, University Park, PA
Pelargonium Synopsis Prepared by:
D.G. Lemon, Oglevee Ltd., Connellsville, PA
PETUNIA (Solanaceae)
Introduction:
The genus Petunia is comprised of approximately 30 species of annual
or perennial herbs. Their center of diversity is South America, with the majority
of species native to Argentina, Brazil, Paraguay, and Uruguay. The Brazilian
states of Parana, Rio Grande do Sul, and Santa Catarina are particularly rich
in Petunia species. One species, P. parviflora, extends from South
America northward to Cuba, Mexico, Texas, Arizona, Florida, California, and
New Jersey.
The early literature concerning taxonomy and nomenclature is confusing and
contradictory, and disagreement still exists today. There have been no recent
studies on the ecology and evolution of the genus Petunia. Generally,
four species are considered to be the parents of the Garden Petunia [=
P. x hybrida Hort. Vilm.-Andr.]: P. axillaris, P. inflata,
P. parodii, and P. violacea. These four species have n= 7 as the
chromosome number, whereas P. parviflora has n = 9 as the chromosome
number. Petunia axillaris and P. parodii are white-flowered species,
with P. parodii having a much longer corolla tube. Petunia inflata
and P. violacea have magenta (mallow purple) flowers; some taxonomists
do not consider these two species to be distinct and have grouped them together
as P. integrifolia var integrifolia (l). Petunia parviflora has
small flowers and succulent-like foliage, and is generally used as a rapid-growing
annual ground cover or hanging basket plant.
In 1990, petunia had a wholesale value of $124.3 million for plant producers
of $10,000 or more in gross sales. The 1991 wholesale value of petunias was
$113.3 million for plant producers of $100,000 or more in gross sales. Petunia
ranks second in importance among bedding plants produced in the United States
and comprises approximately 12.8% of the total crop mix grown by bedding plant
producers.
Present Germplasm Activities:
Most breeding activities are conducted by private companies, including Bodger
Seeds, Ltd (Lompoc, CA), Goldsmith Seeds Inc. (Gilroy, CA), PanAmerican Seed
Co. (Elbum, IL), Sakata Seed Corp. (Yokohama, Japan), S & G Seeds (Enkhuizen,
Holland), and Takii & Company, Ltd. (Kyoto, Japan), and these companies
mainly work with P. x hybrida.
The NPGS priority site for Petunia germplasm is the Northeast Regional
Plant Introduction Station (NRPIS) at Geneva, NY. Five species accessions (two
P. axillaris and three P. integrifolia) and 96 P. x hybrida
accessions (made up of line-bred and hybrid cultivars) are stored at NSSL. Many
of the NSSL accessions are 20 to 30 years old and are declining in viability.
Status of Crop Vulnerability:
The status of indigenous populations of Petunia is unknown because there
have not been any collecting expeditions for several years. Because few species
form the genetic base of present-day cultivars, the genetic diversity could
be considered to be low even though there are probably 300+ cultivars presently
in cultivation. Currently, the major shortcomings of the crop are disease susceptibility
and poor field performance during rainy weather. Commercial cultivars vary in
their susceptibility to Alternaria, Botrytis, Phytophthora, Pythium, Rhizoctonia,
and Sclerotinia.
Germplasm Needs:
A. Collection - Emphasis should be placed on collecting material from indigenous
populations. The collection of hybrid cultivars should be a low priority, but
the collection of line-bred cultivars should be second priority to collecting
indigenous species. Many of the old line-bred cultivars are being lost but do
contain considerable diversity.
B. Evaluation - Accessions should be evaluated for the following traits: growth
habit; plant vigor; foliage color; flower size, color (limb and throat), and
substance; fertility and self-compatibility; and resistance to disease, slugs,
and air pollution. Novel growth habits, flower forms, and flower colors should
be noted.
C. Enhancement - Germplasm enhancement activities should be subordinate to
germplasm collection, evaluation, and preservation.
D. Preservation - The majority of Petunia germplasm used in plant improvement
programs is maintained by private seed companies. NPGS should emphasize the
collection and maintenance of true-to-type populations for Petunia species and
older line-bred cultivars.
Recommendations:
The first priority should be the collection of the important Petunia
species from indigenous populations in order to preserve the wild germplasm
for plant improvement programs. Secondly, the number of NPGS accessions should
be greatly increased for line-bred cultivars and greatly decreased for hybrid
cultivars. Hybrid cultivars are easily obtained from commercial firms. Thirdly,
the collected material should be thoroughly evaluated for disease resistance
and horticultural traits.
Researchers that may be contacted for additional information:
L.C. Ewart, Michigan State University, East Lansing, MI
E. Leue, PanAmerican Seed Co., Elbum, IL
Petunia Synopsis Prepared by:
L.C. Ewart, Michigan State University, East Lansing, MI
SPATHIPHYLLUM (Araceae)
Introduction:
The genus Spathiphyllum consists of about 35 species of tropical perennial
herbs. Spathiphyllum are grown commercially as potted ornamental foliage
plants and, in dollar value, consistently rank in the top 10 among all foliage
plants grown. They are especially valued for their large showy white spathes
that subtend the inflorescence. Commercial cultivars are mostly propagated asexually.
Present Germplasm Activities:
Germplasm enhancement and breeding research on Spathiphyllum are being
conducted by the Florida AES at Apopka, Florida. Program goals include breeding
for disease resistance, improved branching, foliar variegation and continuous
bloom cycle. The NPGS priority site for Spathiphyllum germplasm is CR-MIA
(Miami, FL). The NPGS does not contain any Spathiphyllum accessions at
the present time.
Status of Crop Vulnerability:
The genetic diversity of approximately 25 major spathiphyllum cultivars grown
is quite small. Most cultivars are derived from S. 'Mauna Loa'. 'Mauna Loa'
was a seed-propagated cultivar of unknown origin, until the mid 1970's when
tissue culture became a major propagation method. Improved forms of 'Mauna Loa'
were obtained from seedling populations or mutants found among cultured plants.
Hybrids of 'Mauna Loa' with S. wallissii produced some important cultivars
and thus enhanced genetic diversity. Spathiphyllum wallissii apparently
was closely related to 'Mauna Loa' as the hybrids are fully fertile and intercross
readily. No other Spathiphyllum species have been incorporated into commercial
cultivars, although attempts are currently underway.
Almost all commercial cultivars produced are asexually propagated via tissue
culture and are susceptible to Cylindrocladium spathiphylli, a fungal
stem and root rot for which there is no effective chemical control. Two collected
species, S. florabundum and S. cannifolium have resistance to
this fungal disease. However, genetic barriers prevent hybridization of these
species with commercial cultivars. Therefore, collection of wild germplasm may
find other sources of resistance that can be introduced into commercial cultivars.
Most commercial Spathiphyllum cultivars are seasonal bloomers (January-June)
and require chemical treatment to flower at other times of the year. Collection
of germplasm with year-round flowering patterns could eliminate the need for
chemical treatments.
Germplasm Needs:
A. Collection - Emphasis should be placed on material collected from indigenous
populations throughout the tropics. New germplasm of S. florabundum and
S.cannifolium would be extremely useful to breeders for conferring disease
resistance and recurrent flowering into new cultivars.
B. Evaluation - Plant introductions should be evaluated for resistance to
Cylindrocladium, growth habit, leaf shape and size, degree of branching,
flower size and flowering cycle.
C. Enhancement - There is a breeding program at the Florida AES, but additional
research is needed to conduct screening for disease resistance and find new
sources for resistance.
D. Preservation - The majority of Spathiphyllum germplasm is preserved
by private plant collectors or botanic gardens. Maintaining germplasm is difficult
because plants become rather large and require periodic asexual propagation
(division). In addition, plants should be kept in a shaded greenhouse or similar
enclosed structure and must be grown at high minimum temperatures.
Recommendations:
Priority of Actions - Germplasm of the important Spathiphyllum species
(S. florabundum and S. cannifolium, plus new species not in cultivation)
should be collected from indigenous populations in order to preserve wild material.
Collected material should be disseminated to breeders as use in plant improvement
programs.
Researchers that may be contacted for additional information:
R.J. Henny, University of Florida, Apopka, FL
Spathiphyllum Synopsis Prepared by:
R.J. Henny, University of Florida, Apopka, FL
VERBENA (Verbenaceae)
Introduction:
The genus Verbena is comprised of approximately 200 species of annual
or perennial herbs or subshrubs. The species are native mostly to tropical and
subtropical North and South America. Verbena is increasing in economic
importance, and plants are grown in annual and perennial gardens and in hanging
baskets. The domestic wholesale value of verbena seeds and plants is
estimated at about $1 million annually.
Several Verbena species and hybrids are cultivated. They include the
following:
Verbena bipinnatifida (Dakota Vervain), native to North America, is
a prostrate perennial that grows about 40 cm tall and has dense, corymblike
spikes of lilac-purple flowers.
Verbena bonariensis, native to South America, is an upright annual
or perennial that grows about 120 cm tall and has dense spikes of lilac flowers
(n = 14).
Verbena canadensis (Rose Verbena), native to North America, is a perennial
with creeping, decumbent, or ascending stems and spikes with reddish-purple,
lilac, rose, or white flowers (n = 15).
Verbena x hybrids (Garden Verbena) is a variable species that
is assumed to be an interspecific hybrid between V. peruviana and other
species (n = 10, 20). The majority of the Verbena cultivars sold commercially
are derived from this hybrid. The species is a decumbent or creeping perennial
(but grown mainly as an annual) with flattish, corymblike spikes with pink,
red, white, blue, yellow, purple, or bicolored flowers.
Verbena peruviana, native to Argentina, Brazil, and Chile, is
a perennial (but grown mainly as an annual) with procumbent stems and corymblike
spikes with scarlet or crimson flowers (n = 5).
Verbena rigida (Vervain), native to Argentina and Brazil, is a perennial
that grows from 30 to 60 cm in height. with erect or ascending stems and spikes
with purple or magenta flowers (n = 21).
Verbena tenuisecta (Moss Vervain), native to South America,
is a perennial that grows to 25 cm in height, and has decumbent or ascending
stems and corymblike spikes with blue, purple, violet or lilac flowers.
Present Germplasm Activities:
Most breeding work is being done in the private sector using a very limited
germplasm base. The NPGS priority site for Verbena is NCRPIS (Ames, IA).
The NCRPIS Verbena collection contains four accessions (V. halei,
V. hastata, V. officinalis, and V. urticifolia), and the
NSSL maintains seed of 19 Verbena cultivars.
Status of Crop Vulnerability:
Most of the North American species have a widespread distribution and are therefore
not threatened. In regard to the South American species, the status of indigenous
populations is not known.
Germplasm Needs:
A. Collection - Emphasis should be placed on re-collecting the known South
American species, and also collecting germplasm of previously unknown species.
B. Evaluation - Accessions should be evaluated by NPGS personnel and also
by private companies.
C. Enhancement - It should be very useful if AES or NPGS personnel could handle
a small project with Verbena. Certainly more work needs to be done on
improving disease resistance and seed germination for this crop.
D. Preservation - Verbena tends to be predominantly self-pollinated
so isolation should not be a major problem. The small-flowered species self,
but many North American species do outcross and will hybridize with related
species.
Recommendations:
Germplasm of known and new Verbena species needs to be collected from
South America, evaluated at several locations, and maintained in an area with
a dry, mild climate.
Researchers that may be contacted for additional information:
D.G. Lemon, Oglevee Ltd., Connellsville, PA
Verbena Synopsis Prepared by:
D.G. Lemon, Oglevee Ltd., Connellsville, PA
ZANTEDESCHIA (Araceae)
Introduction:
The genus Zantedeschia, commonly referred to as callas, calla lilies
and spring calla lilies, has six species and two subspecies of horticultural
significance. They are all indigineous to southern Africa, primarily in the
northern Transvaal range. Zantedeschia species and cultivars can be split
into two groups: the Common Calla group consisting of Z. aethiopica,
and the Spring Calla group consisting of the other five species.
The most familiar Zantedeschia species is Z. aethiopica, the
Common Calla (2n = 32). The species is primarily used as a cut flower in wedding
and funeral bouqets. The large spathe is pure white and up to 20 cm long and
the bright yellow spadix is 6 to 10 cm long. Leaves are glabrous, immaculate
(not spotted), usually broadly ovate, and supported by long, fleshy petioles.
Rhizomes of Z. aethiopica tend to be more elongated or columnar than
species in the Spring Calla group. The species is distributed beyond the winter
rainfall area of the Cape, extending from the eastern coastal districts to Natal
and the mountains of the Orange Free State, northern Transvaal, and Lesotho.
It is often found in moist and marshy areas, and is less prone to bulb rots.
Variations in type are not uncommon in cultivation. Occasional dwarf or fragrant
types are discovered, such as 'Childsiana' and 'Onorata.' Other variations include
types with green-white bicolored spathes, blush pink spathes, maculated leaves,
and dormant types. Approximately two million bulbs (rhizomes) of Z. aethiopica
are sold annually (worldwide).
The Spring Calla group (also referred to Colored or Miniature Callas) consists
of the five remaining Zantedeschia species (2n = 32). The rhizomes tend
to be flatter and wider than Z. aethiopica. Spring Callas are grown both
for cutflowers and as potted plants, and have exhibited a worldwide increase
in popularity during the past decade. Sales from California alone are three
million bulbs annually, and worldwide sales are significant. Spring Callas are
more difficult to grow than Z. aethiopica, primarily due to susceptibility
to soft rots. Few barriers exist to hybridization between species within this
group, resulting in a great diversity of flower colors and plant habits.
The Pink (or Red) Calla (Z. rehmannii) is the most suitable species
for cultivation in pots. As a consequence, it is the main species used for breeding
of pot-plant cultivars. Spathe color is commonly blush pink but can vary from
almost white to deep purple. Leaves are lanceolate, up to 40 cm long, 2 to 7
cm wide, immaculate, and glabrous. The species is native to rocky slopes and
forest margins at medium to high altitudes from Harrismith in northern Natal,
through Swaziland, and extending to southern and eastern Transvaal. Pink Calla
has intermediate susceptibility to Erwinia soft rot and moderate tolerance
to Dasheen Mosaic Virus (DMV).
The Golden (or Yellow) Calla (Z. elliottiana) is a robust species with lemon-yellow
to gold, orange or rusty red spathes. The orbicular-ovate, deeply cordate leaves
are up to 27 cm in length and nearly as broad, with many translucent maculations
(spots). Golden Calla produces large rhizomes, is moderately floriferous, and
is important economically as a cut flower. The type is known only from plants
in cultivation; there are no known specimens of this species in the wild. Golden
Calla is moderately tolerant to DMV but is the most susceptible Zantedeschia
species to Erwinia soft rot.
Zantedeschia pentiandii is superficially similar to Z. elliottiana
but differs in that the leaves are usually immaculate, oblong-elliptic to oblong-lanceolate,
hastate, and up to 35 cm long and 15 cm wide. The spathe is lemon-chrome to
deep yellow, usually with a purple blotch at the base of the spadix interior.
Although vigorous, rhizome growth is slower and plants are less floriferous
than Z. elliottiana. However, the species has distinctly greater resistance
to Erwinia soft rot, giving greater economic importance to the species
in the future. The species commonly occurs in rocky terrain and by small streams
on grassy slopes, and is restricted to the Mapoch region of the eastern Transvaal.
Zantedeschia jucunda is little known in cultivation but is similar to
Z. pentlandii in plant size and flower color. Leaves, however, are similar
to Z. albomaculata, being triangular-hastate, densely maculate, 17 to
30 cm long, and 5 to 15 cm wide. The spathe is golden-yellow with a purple blotch.
The species is restricted to the Magnet Heights region of the Lulu Mountains,
Sckhukhuniland. The responses of Z. jucunda to DMV and Erwinia
soft rot are not known.
The Spotted Calla (Z. albomaculata) has three recognized subspecies
whose aggregate distribution extends through Natal, Lesotho, Swaziland, and
the eastern Transvaal, and continues north into Zambia and Angola. The species
is generally characterized by vigorous, strongly maculate leaves that are 40
to 75 cm in length. The 2.5- to 17-cm long spathes range from white to cream,
pale yellow, or coral in color. Cultivated plants exhibit good rhizome development.
The subspecies exhibit differences in leaf shape, maculation intensity, and
flower color. Zantedeschia albomaculata ssp. albomaculata
has conspicuously maculate, triangular, oblong-hastate leaves and white (rarely
pink or pale yellow) spathes. Zantedeschia albomaculata ssp. macrocarpa
has sparsely maculate leaves, broad creamy-white spathes, and large fruit. Zantedeschia
albomaculata ssp. valida is a robust plant to 80 cm tall, with immaculate
leaves and ivory-to cream-colored spathes. Spotted Calla demonstrates the highest
tolerance to Erwinia soft rot within the genus Zantedeschia, but
low tolerance to virus infection. This species may be a potential source of
genes controlling disease resistance, vigor, and flower color.
Present Germplasm Activities:
Current breeding in the United States is primarily limited to Golden State
Bulb Growers (GSBG), formerly Brown Bulb Ranch, located in the Monterey Bay
area of central California. GSBG's improvement efforts began nearly half a century
ago and have focused on the Spring Calla group. Since 1988, GSBG has supported
a breeding program encompassing most species of the Spring Calla group and,
to a lesser extent, the Common Calla. Research at universities and other public
institutions is concentrated on cultural problems and not on genetics or breeding.
New Zealand researchers have been involved with Zantedeschia improvement
since the 1930s. In the 1980s, the New Zealand calla producers coordinated and
funded an organized breeding effort under the auspices of the International
Calla Association (ICA). The ICA has exerted less influence in recent years
and has been surpassed by several small firms. We are not aware of any private
companies or public institutions in New Zealand, Australia, or South Africa
that are preserving Zantedeschia germplasm. There are no Zantedeschia
accessions within the NPGS, nor has an NPGS priority site for Zantedeschia
germplasm been designated.
Status of Crop Vulnerability:
South Africa is the center of genetic diversity for Zantedeschia. The
current status of indigenous populations is not known. However, Z. elliottiana
is not currently found in the wild, and this is probably true of other local
variants due to habitat erosion and collection.
Disease susceptibility, particularly to Erwinia soft rot, can lead to
severe plant losses at virtually any time of year. The pathogens inciting soft
rot are ubiquitous, are primary as well as secondary pathogens in dormant and
actively growing rhizomes, and cannot be adequately controlled by chemical means.
The Spring Calla group is highly susceptible, although variation exists for
tolerance. Some Z. aethiopica clones demonstrate moderate to high resistance,
and efforts are being made to transfer resistance from this species to the Spring
Calla group. Virus infection can also devastate calla plantings. The major viruses
of Zantedeschia are DMV and (to a lesser extent) Tomato Spotted Wilt
Virus (TSWV). Genetic variation appears to exist for DMV symptom expression
but not for true resistance. The primary fungal diseases are root rots incited
by Phytophthora and Rhizoctonia, and leaf spots incited by Alternatia
and Cercospora.
Germplasm Needs:
Current enhancement programs rely on variation from a relatively narrow genetic
base, i.e., commercial cultivars. It would be highly desirable to broaden the
genetic base by incorporating wild germplasm from several Zantedeschia
species.
A. Collection - Exploration and collection should be the primary activity
of the NPGS. It should focus on the Transvaal region of South Africa and extend
beyond the Transvaal for some species. All Zantedeschia species should
be collected. However, due to the need for greater disease resistance and improved
plant habit, special interest should be placed on Z. albomaculata (white
and blush spathes), Z. pentlandii (yellow spathes), and Z. rehmannii
(pink spathes). Emphasis should be placed on selecting clones that exhibit novel
traits, such as a unique spathe color or plant habit. Since Zantedeschia
species are primarily autogamous, plant collecting could be performed with minimum
impact to natural populations by tagging flowering plants in situ and returning
later to collect mature seed. Alternatively, intact plants (rhizomes) may be
collected during one trip.
B. Evaluation - The primary limitation to commercial production of Zantedeschia
is disease susceptibility. Therefore, screening for disease resistance on new
and existing accessions is needed. Currently, little or no disease resistance
screening programs exist. Floriferousness in relationship to rhizome size also
should be evaluated. Simple descriptive notes on plant habit and spathe characteristics
(color, shape, and size) should be recorded.
C. Enhancement - Private industry would be responsible for all enhancement
and breeding activities. Since commercial cultivars are clonally propagated,
some novel selections from wild germplasm may not need additional breeding and
would only require mass propagation before release.
D. Preservation - Zantedeschia rhizomes are not difficult to maintain
if they protected against soft rot or virus infections. Rhizomes are best maintained
in pots and grown annually. Seed is relatively large (1 to 3 mm) and will remain
viable for a minimum of 5 to 7 years if stored at low humidity and temperatures
near 0oC. Minimum isolation of plants is needed because Zantedeschia
is primarily autogamous. The number of seeds per inflorescence ranges from 6
to 50. True species, their variants, and many cultivars are relatively true-breeding;
therefore, much of the germplasm may be preserved as seed stocks. Plants begin
flowering within 2 to 3 years from seed sowing. Zantedeschia germplasm
should be maintained in a region with a mild temperate climate, and preferably
inside a greenhouse or screenhouse. Good sanitation practices should be exercised
throughout crop growth. Due to the relative ease of germplasm preservation,
NPGS holdings should amount to 15 to 50 accessions per species. Non-stable interspecific
mixes could be maintained in small populations of 40 to 70 plants. Current cultivars
could be maintained with 7 to 10 accessions.
Recommendations:
Wild germplasm should be collected, with emphasis on obtaining unusual as well
as typical plants from several populations of each species and subspecies. Non
-destructive collecting methods are somewhat more costly but are possible. Accessions
should be screened for disease resistance. Preservation and descriptive notes
on plant traits are relatively straightforward tasks.
Researchers that may be contacted for additional information:
P. Beckman, Golden State Bulb Growers, Watsonville, CA
Zantedeschia Synopsis Prepared by:
P. Beckman, Golden State Bulb Growers, Watsonville, CA
ZINNIA (Asteraceae)
Introduction:
The genus Zinnia consists of approximately 20 species of annual or.
perennial herbs or low shrubs, all indigenous to the western hemisphere. All
of the species except Z. peruviana are restricted to North America. The
center of genetic diversity for Zinnia is Mexico.
Three species of Zinnia are cultivated widely and are grown commercially
as bedding plants and/or cut flowers: Z. Wolacea Cav. [syn. Z. elegans
Jacq.), Zinnia haageana Regel., and Zinnia angustifolia H.B.K.
(syn. Z. linearis Benth.). The most widely cultivated species is Z.
violacea, a herbaceous annual that is grown for its large, showy inflorescences
and diversity of ray floret colors and petal forms. Plants are erect, 9-200
cm in height, sparsely branched, with large ovate to lanceolate leaves; cultivated
forms have one to several whorls of ray florets. It is distributed from Sinaloa
and Durango to Guerrero at elevations from 600 to 1800 meters, and flowers from
March to November. The species is endemic to openings in woodlands, grassy and
weedy places, old fields, roadsides, and ditches, in open oak forest or tropical
deciduous forest. Landrace types are widely grown in Mexican household gardens.
The chromosome number is n = 12.
Zinnia haageana is a herbaceous annual with an erect or decumbent habit,
ranging up to 60 cm in height, with lanceolate leaves, and 2-4.5 cm wide inflorescences
with a single whorl of solid or bicolored ray florets. Cultivated forms often
have several whorls of ray florets. The species is found from Jalisco to Guerrero
at elevations from 900 to 2000 meters, and flowers from July to November. It
is endemic to grasslands, grassy or rocky hills, wet meadows and fields, roadsides,
and disturbed habitats. The chromosome number is n = 12.
Zinnia angustifolia is a herbaceous annual exhibiting an erect or decumbent
habit. Plants are 20-40 cm in height, profusely branched, with linear to oblong-elliptic
leaves and masses of small inflorescences (1.5-3.5 cm in diameter) with orange
or white ray florets in a single whorl. The species ranges from Sonora and Chihuahua
to Michoacan at elevations from 60 to 2100 meters, and flowers from July to
January. It is endemic to rocky or grassy hills, lava-flows, clearings and woodland
openings, often in disturbed habitats, in oak or oak-pine forest, tropical deciduous
forest, and savannahs. The chromosome number is n = II.
Zinnia violacea is a major seed packet item in North America, but represents
only = 1 % of the total plants produced in a typical bedding plant operation.
Commercial growers attribute the low percentage of Z. violacea grown as bedding
plants to high seed costs and difficulties in producing high-quality plants.
Production difficulties include disease susceptibility, nonuniformity of flowering
at sales time, and excessive plant height. Improvements in disease resistance,
uniformity of flowering, plant habit, and seed yield are needed.
Present Germplasm Activities:
Germplasm enhancement on Zinnia is currently being conducted by the
Massachusetts AES (Amherst, MA) and the Michigan AES (East Lansing, MI). The
goals of the AES programs include improved disease resistance, enhanced branching,
reduced leaf width (reduced leaf area), and novel flower colors/growth habits.
The NPGS priority site for Zinnia is NCRPIS (Ames, IA). Activities at
NCRPIS include collection, evaluation, and preservation of zinnia germplasm.
Status of Crop Vulnerability:
The status of indigenous populations of Zinnia was surveyed in a fall
1993 exploration to Mexico. In northern and central Mexico, Z. peruwana
was extremely common in distrubed habitats, Z. violacea was cultivated
in household gardens, and Z. haageana and Z. bicolor were occasionally
found in grasslands and rocky scrubland. Other annual species were difficult
to locate. Among the shrubby Zinnia species, Z. acerosa was distributed
widely in creosote bush and thom scrub, Z. juniperifolia was restricted
to mid-elevation slopes with juniper and pinion near Saltillo, and Z. citrea
was relocated from the type locality.
The level of genetic diversity in commercial zinnia cultivars is unknown.
Over 50 cultivars of Z. violacea are available commercially, including
open-pollinated cultivars and F1 hybrids; most cultivars are diploid (2n = 24),
although a few tetraploids (2n = 48) have been developed. Three open-pollinated
cultivars of Z. haageana are available commercially, including two diploids
(2n = 24) and one tetraploid (2n = 48). Three open-pollinated cultivars of Z.
angustifolia var. angustifolia are sold commercially; they are ostensibly
diploid (2n = 22).
In the United States, three pathogens incite moderate to severe epiphytotics
within Z. violacea plantings: Alternaria zinniae Pape causing
alternaria blight, Erysiphe cichoracearum DC. ex Merat causing powdery
mildew, and Xanthomonas campestris pv. zinniae Hopkins & Dowson
causing bacterial leaf and flower spot. Powdery mildew is the most serious disease
of Z. violacea and Z. haageana in the United States, and susceptibility
of Z. violacea cultivars to powdery mildew appears to be a major contributing
factor to declining seed sales. Alternaria zinniae and Xanthomonas
campestris pv. zinniae are seed-born pathogens and are thus a major
concern for both seed producers and commercial growers. Commercial cultivars
of Z. violacea are either highly susceptible or exhibit limited resistance
to these three pathogens. Zinnia angustifolia var. angustifolia
is highly resistant or immune to all three pathogens, and this species has been
crossed with Z. violacea. The interspecific hybrids (= Z. marylandica)
exhibit high levels of resistance to Alternaria zinniae and Erysiphe
cichoracearum, and moderate to high levels of resistance to Xanthomonas
campestris pv. zinniae. However, plants of Z. marylandica
are less suitable than Z. violacea as a cut flower, primarily due to
smaller inflorescences and fewer ray florets in the former. Identification of
disease resistance within Z. violacea would be of considerable value.
Germplasm Needs:
A. Collection - Emphasis should be placed on material collected from indigenous
populations. Currently, NCRPIS has 56 accessions of Zinnia (6 Z. angustifolia;
2 Z. grandiflora; 9 Z. haageana; 12 Z. peruviana; 9 Z.
violacea; and 5 other species). In additon, NSSL holds 1 Z. angustifolia,
2 Z. peruviana, 4 Z. violacea, and 19 unidentified Zinnia
species (primarily Z. violacea cultivars). The NPGS holdings should be
expanded significantly to include approximately 15 accessions of each Zinnia
species that is not in cultivation, and approximately 50 accessions for each
of the economically-important species, i.e., Z. angustifolia, Z. haageana,
and Z. violacea. Sources of resistance to Alternaria zinniae,
Erysiphe cichoracearum, and Xanthomonas campestris pv. zinniae
are needed in Z. violacea. Small-leaved populations of Z. violacea
would be useful to breeders. Novel growth habits, flower forms, and flower colors
are needed in Z. angustifolia, Z. haageana, and Z. violacea.
B. Evaluation - Plant introductions should be systematically screened for
disease resistance and evaluated for the following characters: plant habit,
leaf shape/size,degree of branching, flower diameter, shape/number of ray florets,
and ray floret color.
C. Enhancement - There are breeding programs in progress at the Massachusetts
AES and the Michigan AES, but more research is needed to identify new sources
of disease resistance that can be used as germplasm in plant improvement programs.
Germplasm enhancement activities at the NPGS priority site for Zinnia
should be subordinate to collection, evaluation, and preservation of germplasm.
D. Preservation - The majority of the Zinnia germplasm used in domestic
improvement programs is maintained by private seed companies. Within the NPGS,
emphasis should be placed on developing and maintaining populations that are
representative of the germplasm of an area rather on single plant collections.
Zinnias are cross-pollinated and have a sporophytically-controlled self
incompatibility (SI) system. Plant introductions thus require isolation during
seed production in order to maintain purity, and several SI genotypes are needed
for intercrossing within PIs.
Recommendations:
Priority of Actions - Germplasm of the important Zinnia species (Z.
angustifolia, Z. haageana, and Z. violacea) needs to be collected
from indigenous populations in order to preserve the wild material that still
exists. Secondly, the NPGS holdings should be expanded to include accessions
of each Zinnia species that is not under cultivation. The collected material
needs to be thoroughly evaluated in replicated trials for horticultural traits.
These accessions could then be used by breeders as germplasm in plant improvement
programs.
Researchers that may be contacted for additional information:
T.H. Boyle, University of Massachusetts, Amherst, MA
L.C. Ewart, Michigan State University, East Lansing, MI
M.P. Widrlechner, USDA/ARS, NCRPIS, Ames, IA
Zinnia Synopsis Prepared by:
T.H. Boyle, University of Massachusetts, Amherst, MA
M.P. Widrlechner, USDA/ARS, NCRPIS, Ames, IA
VII. Priority Genera that
are Currently Without a Synopsis:
Genus Family Number of Species: Center(s) of Diversity
Alstroemeria Alstroemeriaceae approx. 60; Brazil, Chile, & Peru
Aster Asteraceae 250-500; N. & S. America, Europe, Asia
Caladium Araceae approx. 15; tropical America
Euphorbia Euphorbiaceae > 1,600; W. Hemisphere (sp. of interest)
Kalanchoe Crassulaceae approx. 125; Africa & Madagascar
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