Fleshy Owl's-clover

Castilleja campestris ssp. succulenta

Description

Castilleja campestris ssp. succulenta, (fleshy owl's-clover) is a glabrous, hemiparasitic annual herb belonging to the snapdragon family (Scrophulariaceae). The stems are simple or branched, generally 2-10 in (5-25 cm) tall with brittle-succulent or brittle-fleshy, entire, alternate leaves. The branches end in a dense, short, and green inflorescence with bracts equaling or exceeding the bright yellow to white flowers that appear in May. C. campestris ssp. succulenta occurs with C. campestris ssp. campestris in Stanislaus County, but the latter can be distinguished by its usually more brittle leaves, shorter bracts, larger corollas, and longer stigmata.

Robert Hoover originally described this plant in 1936 as Orthocarpus campestris var. succulentus from specimens at its type locality in beds of vernal pools near Ryer, Merced County. He subsequently elevated it to the full species O. succulentus 30 years later, distinguishing it from O. campestris on the basis of leaf and bract shape and flexibility, corolla color, and anther cell length. T.I. Chuang and L.R. Heckard significantly revised Orthocarpus in 1991, subsuming most of what had been called Orthocarpus into the genus Castilleja. They also proposed the new combination C. campestris ssp. succulenta.

Habitat

Fleshy owl's-clover occurs at the edges of vernal (or temporary) pools.

Distribution

Fleshy owl's-clover discontinuously occurs in the San Joaquin Valley over a range of 66 mi (145 km) extending through northern Fresno, western Madera, eastern Merced, southeastern San Joaquin, and Stanislaus Counties. This small annual plant was formerly more widespread in the Central Valley and is now extirpated from its type locality near Ryer in Merced County. Additionally, three populations in Fresno County have not been observed for some years and are possibly extirpated.

One population occurs on lands managed by the Bureau of Reclamation (BOR), one on lands owned by the California Department of Transportation, and two populations on land managed by the Bureau of Land Management (BLM). Thirty-two populations occur on private lands. Of these populations, seven occur at the Flying M Ranch, where the Nature Conservancy (TNC) has a conservation easement.

Threats

Fleshy owl's-clover is primarily threatened by habit destruction brought about by urban development and conversion of land to agriculture. Of the 36 extant populations of this taxon, nearly half are threatened by at least one of the following—urbanization, agricultural land conversion, discing, trampling, a flood control project, and a proposed highway expansion project.

Housing tract developments imperil two populations of C. campestris ssp. succulenta in Fresno County and one population in Madera County. Three proposed gravel and aggregate mining projects, two in Sacramento County and one in Fresno County, threaten to destroy vernal pool habitat containing populations of this plant. The Merced County Landfill will destroy vernal pools containing C. campestris ssp. succulenta. A proposed landfill threatens one population of this taxon in Fresno County. Three populations of C. campestris ssp. succulenta are threatened in Madera County by proposed expansion of State Highway 41.

Agricultural land conversion now threatens one population of this taxon in Madera County and one in Fresno County. Discing has likely eliminated one population of this plant in Fresno County. The Merced County Stream Channel Project of the U.S. Army Corps of Engineers threatens four populations of C. campestris ssp. succulenta in Merced County within the San Joaquin Valley.

Conservation and Recovery

One population of the fleshy owl's-clover occurs on lands managed by the BOR, two are on land managed by the BLM, and one is on land owned by the California Department of Transportation. These government-owned sites should be protected from any threatening activities. Another seven populations occur on the privately owned Flying M Ranch, where TNC (a private conservation organization) holds a conservation easement intended to protect the natural habitat. The other 25 populations of the fleshy owl's-clover occur on non-conserved private lands, where they are at risk from development activities and other disturbances. The critical habitat of the largest nonconserved populations on private land must be protected. This could be done by acquiring the land and establishing ecological reserves, or by negotiating conservation easements with the landowners. The known populations of the fleshy owl's-clover should be monitored, and research undertaken into its biology and habitat needs.

Contacts

U. S. Fish and Wildlife
Service Sacramento Fish and Wildlife Office
Federal Building
2800 Cottage Way, Room W-2605
Sacramento, California 95825-1846
Telephone: (916) 414-6600
Fax: (916) 460-4619

U. S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
Eastside Federal Building
911 N. E. 11th Ave.
Portland, Oregon 97232-4181
Telephone: (503) 231-6121
http://pacific.fws.gov/

Reference

U.S. Fish and Wildlife Service. 26 March 1997. "Endangered and Threatened Wildlife and Plants; Determination of Endangered Status for Three Plants and Threatened Status for Five Plants from Vernal Pools in the Central Valley of California." Federal Register 62(58): 14338-14352.