Santa Clara Valley Dudleya
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Sacramento Fish & Wildlife Office

Species Account

SANTA CLARA VALLEY DUDLEYA
(Dudleya setchellii)

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:

Santa Clara Valley dudleya (Dudleya setchellii) is a low-growing perennial of the stonecrop family (Crassulaceae). It has smooth (glabrous), fleshy leaves, 1 to 3 inches long and 0.3 to 0.6 inch wide. The leaves are oblong, tending to be wider at their base.

Two or three flowering stems grow to heights of 2 to 8 inches in mid to late spring. Flowers bloom in May and June. The pale yellow petals are 0.3 to 0.5 inch long. 

There are two common dudleya species in the area. Canyon dudleya (D. cymosa ssp. cymosa) has bright yellow to red petals rather than pale yellow. It is therefore easily distinguished from Santa Clara Valley dudleya. Diablo Range dudleya (D. cymosa ssp. paniculata) can be distinguished by its leaves, which are also oblong but tend to be wider at their apex. Diablo Range dudleya's flower heads branch more and the flower stems (pedicels) are longer. See Hickman (1993) in General Information about California Plants, below, for detailed information about all of these species.

DISTRIBUTION:

Santa Clara Valley dudleya is restricted to rocky outcrops within serpentine grasslands in Santa Clara County. It is found only in the Coyote Valley area, from San Jose south about 20 miles to San Martin, at elevations of 300-900 feet. Fourteen sites and a total of 12,000-13,000 plants are known to exist.

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 Santa Clara Valley dudleya have adapted to serpentine soils and require them to survive.

SPECIAL CONSIDERATIONS:

Santa Clara dudleya always has been restricted to the Coyote Valley area of Santa Clara County. Eleven of the 14 populations are on private land and are subject to various levels of threat from development, unauthorized dumping and off-road vehicle use.

The species is also vulnerable because of the horticultural appeal of succulents and the slow growth of the plants. The remaining plants are usually not spectacular in flower but may nonetheless appeal to collectors because of their rarity.

A recent survey for the species in Santa Clara County found up to 15 new occurrences and reported seven previously less-documented occurrences from the same general area, together comprising nearly 20,000 individual plants, but did not substantially expand the geographic range of the species. This survey brings the number of dudleya occurrences thought to be extant to 50, and the maximum known number of individuals to about 85,000.

The California Native Plant Society has placed it on List 1B (rare or endangered throughout its range). Although the species has not been officially listed by the State of California, the Department of Fish and Game considers it to be "very threatened."

REFERENCES FOR ADDITIONAL INFORMATION:

Moran, R. 1959. Dudleya. In: H. Jacobsen, A Handbook of Succulent Plants. Blandsford Press, London.

Nakai, K. 1987. Some new and reconsidered California Dudleya (Crassulaceae). Madroño 34:334-353.

Olson, B., and D. Lake. 1991. Status of rare, threatened, and endangered vascular plants in Alameda and Contra Costa counties. 2nd edition. California Native Plant Society, East Bay Chapter.

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: Santa Clara Valley Dudleya Roxanne Bittman © 1989 California Native Plant Society Calphoto ID: 0000 0000 0502 0732

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

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