The Alkali (Scirpus Maritimus L.) and Saltmarsh (S. Robustus Pursh) Bulrushes: A Literature Review

Taxonomy and Distribution

S. Galen Smith
Department of Biology, University of Wisonsin-Whitewater, Whitewater, Wisconsin 53190
Harold A. Kantrud
J. Browning and K.D. Gordon-Gray
University of Natal, Pietermaritzburg, South Africa

Scirpus maritimus L. and S. robustus Pursh belong to a small, worldwide group of the family Cyperaceae, in North America often called the "tuberous bulrushes," that needs a taxonomic revision (Wilson 1981; Hulten and Fries 1986; Goetghebeur and Simpson 1991). Taxonomic confusion as reviewed here is due to disagreement about species boundaries, infraspecific variation, misapplication of names, probable hybridization, and introduction of species. The same name (especially S. maritimus) may refer to more than one species and to hybrids, and several names are correctly or incorrectly used for the same species. For the references reviewed herein, the names and the species to which they apply therefore must be carefully evaluated.

The group of bulrushes is recognized by perennial rhizomatous habit; large, hard, carbohydrate-rich corms or "tubers" on the rhizomes; leafy, sharply triangular stems; leaflike bracts accompanying the inflorescence; large spikelets; and floral scales that are minutely hairy and apically trifid with prominent midrib extensions ("awns"). Fernald (1950) placed these bulrushes in Scirpus section Phyllantheli Beurl. and Koyama (1962) called the group the "Scirpus maritimus complex." Lye (1971), Haines and Lye (1983), and Strong (1993, 1994) placed the group in the genus Schoenoplectus. Other authors (e.g., DeFilipps 1980) treated the group as either Scirpus section Bolboschoenus Ascherson, or, with the division of Scirpus into more natural genera in recent years, segregated the group into the genus Bolboschoenus (Aschers.) Palla (e.g., Hejny 1960; Caspar and Krausch 1980; Koyama 1980; Wilson 1981; Browning and Gordon-Gray 1993; Browning et al. 1995). The group will probably be placed in Bolboschoenus in an upcoming volume of Flora of North America (Flora of North America Editorial Committee. Cyperaceae. Flora of North America north of Mexico. Volume and date to be determined. Oxford University Press, New York, unpublished) in which case the correct names of S. maritimus and S. robustus will be Bolboschoenus maritimus (L.) Palla and Bolboschoenus robustus (Pursh) Sojak (S. Galen Smith, Department of Biology, University of Wisconsin-Whitewater, Whitewater, Wisconsin, personal communication).

For North America, recent taxonomists (Beetle 1942; Fernald 1943, 1950; Koyama 1962; Schuyler 1975; Browning et al. 1995) have interpreted species boundaries variously. Browning et al. (1995) provided several new diagnostic characters using scanning electron microscopy of achenes and argued that hybridization where the species grow together is responsible for much of the taxonomic confusion in this group (see especially Scirpus novae-angliae and S. glaucus below). We herein recognize the following five species for North America: S. maritimus L., S. robustus Pursh, S. fluviatilis (Torr.) Gray, S. novae-angliae Britt., and S. glaucus Lamarck (introduced from the Old World). For North American synonymy we mostly follow Kartesz (1994).

We treat S. maritimus as "s. lat." ("sensu lato", or "in a broad sense") pending further studies because the species is very difficult to delimit and is treated as s. lat. in much of the ecological literature. For North America and Hawaii, some authors (e.g., Beetle 1942; Fernald 1950; Schuyler 1975) segregated most plants of S. maritimus into S. paludosus A. Nelson, while others, especially recently (e.g., Gleason 1952; Koyama 1962, 1990; Gleason and Cronquist 1963, 1991; Hitchcock et al. 1969; Cronquist et al. 1977; Scoggan 1978; Boivin 1992; Smith et al. 1993; Kartesz 1994; Browning et al. 1995) treated S. paludosus as a synonym, variety, or subspecies of S. maritimus. Synonyms of S. maritimus L. for North America as herein treated are: Scirpus brittonianus Piper; S. campestris Britt.; S. fernaldii Bickn.; S. interior Britt.; S. maritimus var. fernaldii (Bickn.) Beetle; S. maritimus var. paludosus (A. Nelson) Kuek.; S. pacificus Britt.; S. paludosus A. Nelson; S. paludosus A. Nelson var. atlanticus Fern.; S. robustus var. campactus Davy ex Jepson; S. robustus Pursh var. paludosus (A. Nelson) Fern.; Bolboschoenus maritimus (L.) Palla; B. maritimus (L.) Palla subsp. paludosus (A. Nelson) T. Koyama; B. paludosus (A. Nels.) Soo; Schoenoplectus maritimus (L.) K. Lye.

For Europe, most recent taxonomists have recognized only Scirpus maritimus but with various subspecies, varieties, and forms (e.g., Suessenguth 1939; Schultze-Motel 1980; Hulten 1964; Hulten and Fries 1986). Some taxa reportedly occur variously in alkaline or acid fresh waters or in waters of greater or lesser salinity (Hejny 1960; Robertus-Koster 1969; Caspar and Krausch 1980). Norlindh (1972) and Dykyjova (1986) reviewed the taxonomy and biogeography of S. maritimus s. lat. in Eurasia. For Flora Europaea, DeFilipps (1980) followed Nordlindh (1972) in recognizing only S. maritimus, placing S. compactus Hoffm. in synonymy, and treating the mostly Asian S. affinis Roth as S. maritimus subsp. affinis (Roth) Nordlindh. In addition, recent work has shown that S. yagara Ohwi (S. fluviatilis subsp. yagara [Ohwi] Koyama) and probable S. maritimus × yagara hybrids occur in Europe and are probably included within the concept of S. maritimus there (Browning et al. 1996).

For eastern Asia, Koyama (1958, 1980) recognized three taxa: S. maritimus, S. fluviatilis subsp. yagara, and S. planiculmis; he also showed that most plants previously called S. planiculmis F. Schmidt belong in S. maritimus and that the true S. planiculmis is a very different Pacific coastal endemic. For Australia, New Zealand, and various southern Pacific islands, taxonomists (e.g., Cook 1947; Wilson 1981) recognize the three species: S. caldwellii V. J. Cook, S. medianus V. J. Cook, and S. fluviatilis. The latter species is also North American. For southern Africa and elsewhere, Browning and Gordon-Gray (1993), Smith (1995), and Browning et al. (1995) showed that S. maritimus s. lat. as previously treated includes S. glaucus Lamarck and probable hybrids (see following sections).

Taxonomists have generally treated trigynous plants (with trifid styles and trigonous achenes) as "typical" S. maritimus (e.g., Ascherson and Graebner 1902-1904; Fernald 1943, 1950; Koyama 1958; Gleason 1952, 1963; Robertus-Koster 1969; Nordlindh 1972; Caspar and Krausch 1980; Boivin 1992) and have placed digynous plants (with bifid styles and lenticular achenes) in various infraspecific taxa such as S. maritimus var. digynus Godron or in separate species such as S. paludosus A. Nels., S. affinis Roth, S. compactus Hoffmann, and S. planiculmis F. Schmidt (misapplied). Trigynous plants are common in Europe and southern Africa but rare in North America (Browning et al. 1995).

Scirpus maritimus and S. robustus differ by very few achene and other characters (e.g., Schuyler 1975; Browning et al. 1995). These species have been confused by several authors, especially on the Pacific coast; for example, Mason (1957), Munz and Keck (1959), and George (1963) erroneously placed S. maritimus in synonymy under S. robustus. Correll and Correll (1975) treated S. robustus under its synonym S. maritimus var. macrostachyus Michx. These two bulrushes are especially variable in their zones of sympatry on the northern Atlantic coast as described by Fernald (1943) and Schuyler (1975) and in California (S. G. Smith, unpublished). Some of this variation is the basis for infraspecific taxa recognized by, for example, Fernald (1943, 1950) and Hulten and Fries (1986). Browning et al. (1995) ascribe much of this variation to hybridization. Synonyms of S. robustus are Bolboschoenus robustus (Pursh) Sojak and Scirpus maritimus L. var. macrostachyus Michx.

Scirpus novae-angliae, known only from northern Atlantic coastal estuaries, is controversial. Beetle (1942), Gleason (1952), and Gleason and Cronquist (1963) placed this bulrush in S. robustus, while Fernald (1950) and Koyama (1962) placed it in S. maritimus. Koyama (1962) reduced S. novae-angliae to var. cylindricus (Torr.) T. Koyama of the unrelated S. subterminalis Torrey. Schuyler (1975), under S. cylindricus, clarified the nomenclature of S. novae-angliae and described its morphology and habitat, and Ferren and Schuyler (1980) further described its habitat. Browning et al. (1995) argued that S. novae-angliae originated as S. fluviatilis × robustus hybrids because it: (1) is morphologically intermediate; (2) grows in habitats intermediate between the saline habitats of S. maritimus and S. robustus and the freshwater habitats of S. fluviatilis; and (3) is known almost only from the zone of sympatry of its putative parents. Synonyms of S. novae-angliae are: S. campestris var. novae-angliae (Britt.) Fern.; S. maritimus var. cylindricus Torr.; S. robustus Pursh var. novae-angliae Beetle; S. cylindricus (Torr.) Britt.; S. subterminalis Torr. var. cylindricus (Torr.) T. Koyama; Bolboschoenus novae- angliae (Britt.) S. G. Smith; and Schoenoplectus novae-angliae (Britt.) M. T. Strong.

Beetle (1942), Mason (1957), George (1963), Munz and Keck (1959, 1973), and Smith et al. (1993) also included a species that they called Scirpus tuberosus Desf. Koyama (1962) reduced this species to S. maritimus var. tuberosus (Desf.) T. Koyama. Smith (1995), however, showed that the name S. tuberosus Desf. is a synonym of S. maritimus, and that S. glaucus Lamarck (Bolboschoenus glaucus [Lam.] S. G. Smith) is a correct name for this species. Browning et al. (1995) showed that S. glaucus and S. maritimus differ greatly in their achene structure, and that many specimens from wildlife refuges, rice fields, and waste sites in California are probably S. glaucus × maritimus hybrids. Scirpus glaucus is widespread in Asia and Africa, where it is often included in the concept of S. maritimus (Browning et al. 1995 and personal communication). Scirpus glaucus was introduced into North America, where it is definitely known from California, Oregon, Idaho, and New York (S. G. Smith, unpublished).

Below we list the common or colloquial names that have been applied to S. maritimus and S. robustus, but possibly erroneously to other closely related species as reviewed above. Besides alkali bulrush (Scott and Wasser 1980), S. maritimus is locally known as bayonet grass, perennial nutsedge, prairie bulrush, purua grass, saltmarsh bulrush, sea club-rush, seacoast bulrush, and tule (Wetmore 1921; Christensen et al. 1947; Fernald 1950; Hyer 1963; Batten 1967; Nakagawa et al. 1973; Kim and De Datta 1974; Yamanaka 1975). Scott and Wasser (1980) prefer the common name saltmarsh bulrush for S. robustus. Others call the plant buttergrass, coco, goose grass, leafy three-cornered grass, leafy three-cornered rush, leafy sedge, leafy three square, leafy three-cornered sedge, nut grass, robust bulrush, saltmeadow bulrush, sea club rush, stout bulrush, triangle sedge, and wild chufa (McAtee 1939; Lay and O'Neil 1942; Lynch et al. 1947; O'Neil 1949; Brown 1959; Beter 1957; Kimble 1958; Linthurst and Seneca 1980; Hackney and Cruz 1982; Payne 1992; Anonymous 1994).

Chromosome numbers reported for S. maritimus worldwide vary from approximately n=40-57 (2n = 80-114) as summarized by Chapman (1974) and Cronquist et al. (1977), and for S. robustus in Massachusetts, n= approximately 53-55 (Hicks 1928). Although these reports demonstrate that aneuploid series occur in this complex, chromosome numbers cannot be definitely assigned to species because the taxonomy is so confused as reviewed above and identifications must be confirmed by study of voucher specimens.

Scirpus maritimus s. lat. is one of the most widely distributed plants of the Northern Hemisphere. The species is more or less circumpolar in boreal and temperate regions on coasts and in the interior (Hulten 1964; Ranwell 1972; Koyama 1980; Hulten and Fries 1986) and ascends to at least 3,000 m in Tibet and 2,900 m in Colorado (Hulten 1964). In Europe, S. maritimus ranges from just above the Arctic Circle on Russia's Kola Peninsula south to the Mediterranean region. This bulrush occurs in much of North America from about 62° N in Alaska's Cook Inlet area and Northwest Territories, to approximately 55° N on James Bay (where disjunct; Riley and McKay 1980), to about 51° N on the Atlantic coast in Quebec and south to Mexico. Scirpus maritimus is absent from the Atlantic coast south of New Jersey and from the gulf coast, except possibly for a small area in Texas. This species is an important member of the Pacific coastal marshes between 35° N and 55° N (Macdonald 1977; Hutchinson 1986). In the interior, S. maritimus occurs in saline places rarely in the East and commonly in the West, south to Missouri and Mexico.

Elsewhere, S. maritimus occurs in Mexico (Saunders and Saunders 1981) and the Hawaiian Islands (Koyama 1990) and is local in South America (West 1977; S. G. Smith and J. Browning, unpublished) and Africa (Browning et al. 1995 and unpublished). Reports of S. maritimus from the southern Pacific (Australia, New Zealand, Tasmania, New Caledonia, etc.; e.g., Congdon 1981) and from the Philippines and New Guinea (e.g., Kern 1974; Kim and De Datta 1974) may refer to S. caldwellii V. J. Cook and other species. Many reports of S. maritimus and S. tuberosus from various warm parts of the Old World, especially in the Middle East, Asia and Africa, may refer to S. glaucus Lam. (Browning et al. 1995 and unpublished).

Scirpus robustus Pursh is definitely known only from saline places at low elevations on or near the coasts of North and South America and the Caribbean (S. G. Smith, unpublished). In North America, this species occurs in the East along most of the Atlantic and gulf coasts from New Brunswick and Prince Edward Island to northern Mexico. According to Shisler (1990), S. robustus is especially common south of Delaware. On the Pacific coast this bulrush is common in the San Francisco Bay region and very local north to Washington and south to Baja California (Smith et al. 1993; S. G. Smith, unpublished). The distributions of S. robustus and S. maritimus overlap along the northeast Atlantic coast, on the Pacific coast, and in a small region near the gulf coast of Texas (S. G. Smith, unpublished).

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