White-Rayed Pentachaeta
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Sacramento Fish & Wildlife Office

Species Account

WHITE-RAYED PENTACHAETA
(Pentachaeta bellidiflora)

CLASSIFICATION: Federal Endangered Species (Federal Register  60:6671  (pdf); February 3, 1995).

CRITICAL HABITAT: None designated.

RECOVERY PLAN: Recovery Plan for Serpentine Soil Species of the San Francisco Bay Area, September 30, 1998 (pdf format)

DESCRIPTION:

White-rayed pentachaeta (Pentachaeta bellidiflora) is a small annual plant of the aster family (Asteraceae). It has a few erect, unbranched stems, 2.5 to 7 inch tall. The stems grow from a slender taproot. The alternate leaves are about 1.8 inch long and very narrow.

Flowers bloom from March to May. Each flower head has many yellow disk flowers and 5 to 16 white to purplish ray flowers. The fruits are tawny, coarse-haired achenes (dry one-seeded fruits). Related species in the San Francisco Bay area, meager pentachaeta (Pentachaeta exilis ssp. exilis) and tiny pentachaeta (P. alsinoides), have no ray flowers. See Hickman (1993) in General Information about California Plants, below, for a detailed description of these species.

Species associated with white-rayed pentachaeta include bird's-eye gilia (Gilia tricolor), blue dicks (Dichelostemma capitatum), blue-eyed grass (Sisyrichium bellum), California buttercup (Ranunculus californicus), California poppy (Eschscholzia californica), earth brodiaea or dwarf clusterlilly (Brodiaea terrestris), denseflower owl's clover or denseflower Indian paintbrush (Castilleja densiflora), royal larkspur (Delphinium variegatum), and yellowray goldfields (Lasthenia glabrata). The threatened bay checkerspot butterfly (Euphydryas editha bayensis) is also found in the area. The threatened Marin dwarf flax is not directly associated with white-rayed pentachaeta, although it occurs in the same vicinity

DISTRIBUTION:

This species grows in serpentine bunchgrass habitat. Historically, it was known from at least nine sites in Marin, San Mateo, Santa Cruz and Monterey counties.

Three populations in Marin County and two in San Mateo County were destroyed by urbanization. One Marin County occurrence was destroyed by off-road vehicles. Suitable habitat remains in two San Mateo County locations, but the species has not been seen at either site in many years.

The species is now known from only one confirmed location in San Mateo County, in the "Triangle" area and adjacent Edgewood County Park. This population was bisected by the construction of California Interstate 280 in the late 1960s. The largest portion of the population occurs in the Triangle, on land administered by the San Francisco Water District. A small remnant remains to the east of Interstate 280, in Edgewood County Park.

Serpentine soils are formed from weathered volcanic (ultramafic) rocks such as serpentinite. dunite, and peridotite. These soils provide a harsh environment for plant growth. Several factors contribute to the inhospitability of serpentine soils to plant growth including: 1) a low calcium-magnesium ratio; 2) lack of essential nutrients such as nitrogen, potassium, and phosphorous; and 3) high concentrations of heavy metals (mineral toxicity). However, species such as white-rayed pentachaeta have adapted to serpentine soils and require them to survive.

SPECIAL CONSIDERATIONS:

White-rayed pentachaeta is threatened by competition from nonnative plant species. This competition becomes a problem when the soils are disturbed. The species is also threatened by proposed trail construction. It is also extremely vulnerable to random events.

This species was listed as endangered by the California Department of Fish and Game in June 1992. The California Native Plant Society has placed it on List 1B (rare or endangered throughout its range).

REFERENCES FOR ADDITIONAL INFORMATION:

U.S. Fish and Wildlife Service. 1995. Endangered and Threatened Wildlife and Plants; Determination of Endangered Status for Ten Plants and Threatened Status for Two Plants From Serpentine Habitats in the San Francisco Bay Region of California. Portland, Oregon.

U.S. Fish and Wildlife Service. 1998.  Recovery Plan for Serpentine Soil Species of the San Francisco Bay Area. Portland, Oregon.

General Information about California Plants

Photo credit: White-Rayed Pentachaeta © 1997 Doreen L. Smith, Calphoto ID: 0000 0000 1101 0138

Prepared by Endangered Species Div., Sacramento Fish & Wildlife Office, U.S. Fish & Wildlife Service

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