California Orcutt Grass

Orcuttia californica

Description

California orcutt grass is a member of the grass family, associated with deep pools of water. It is a small annual that reaches 4 in (10.2 cm) in height, is colored bright green, and secretes sticky droplets that taste bitter. Inflorescences, borne from May through June, consist of seven spikelets arranged in two ranks, with the upper spikelets overlapping on a somewhat twisted axis. The teeth of the lemma (bract enclosing the floret) extend 0.2 in (0.5 cm) long or less. Its teeth are sharply pointed and its terminal bristles are 0.2 in (0.5 cm) long or less. Stems usually are prostrate and the fruit grow from 0.06-0.07 in (1.5-1.8 mm) long. Plants bear soft and straight spreading hairs and the spikelets are remote on the axis below, crowded toward the apex.

Orcuttia californica can be separated from O. inaequalis by being sparsely hairy with a prostrate stem. In addition, the inflorescence has spikelets that are well-separated on the lower part of the axis and are crowded toward the tip.

Habitat

The species occurs in vernal pools which form in areas with Mediterranean climates where slight depressions become seasonally wet or inundated following fall and winter rains. Water remains in these pools for a few months at a time, due to an impervious layer such as hard pan, clay, or basalt beneath the soil surface. Gradual drying occurs during the spring. The pools form on mesa tops or valley floors and are interspersed among very low hills usually referred to as mima mounds.

Distribution

California orcutt grass has historically been reported from at least four locations in Los Angeles County. However, it is currently known from only two localities near Santa Clarita, California (Cruzan Mesa) and near Woodland Hills (Los Angeles County). An occurrence is known from the Carlsberg vernal pool located in the City of Moorpark in Ventura County. The species is also known from the Santa Rosa Plateau, Skunk Hollow, and a site near Hemet (Riverside County).

The species also once occurred near Murrieta Hot Springs, but this population has been extirpated. In San Diego County, O. californica is found in two pools on MCAS Miramar, in the City of Carlsbad (in the same pool as Eryngiurn aristulatum var. parishii, Navarretia fossalis, and the Riverside and San Diego fairy shrimp), and in four pool complexes on Otay Mesa. In Baja California, Mexico, O. californica has been found on Mesa de Colonet and in pools at San Quintin. These Baja populations are believed to still exist, but in danger of being extirpated due to agricultural conversion.

Threats

The U.S. Fish and Wildlife Service (FWS) determined that the present range was being rapidly reduced and the continued existence of the species was being threatened by habitat loss and degradation due to urban and agricultural development, livestock grazing, off-road vehicle use, trampling, invasions from weedy non-native plants, and other factors.

Conservation and Recovery

Three vernal pool groups in southwestern Riverside County also contain this species. One of these complexes is partially preserved within The Nature Conservancy's Santa Rosa Plateau Reserve. Another complex is often plowed and is within the general locality of a conditionally approved residential development. A proposed project in this area includes major improvements to roads and utility crossings that would directly impact 0.2 acres (0.08 hectares) of this watershed. Proposed mitigation consists of experimental watershed creation. Soil sedimentation could still occur as well as impacts to hydro-logic function. Several tract projects, already approved within the watershed, would alter the pool hydrology and adversely impact the species therein. The FWS and California Department of Fish and Game are working to find a buyer for this site.

A third population exists on private unprotected land. One pool near a road in this area was disced. These pools are also potentially threatened by widening of an adjacent road.

The FWS recovery priority of 5C indicates that it is a species facing a high degree of threat and has a low potential for recovery. It may be in conflict with construction or development projects.

Contact

U.S. Fish and Wildlife Service
Regional Office
Eastside Federal Complex
911 N.E. 11th Ave.
Portland, Oregon 97232-4181
Phone: (503) 231-6118
http://pacific.fws.gov/

References

U.S. Fish and Wildlife Service. 3 August 1993. "Endangered and Threatened Wildlife and Plants; Determination of Endangered Status for Three Vernal Pool Plants and the Riverside Fairy Shrimp." Federal Register 58 (147): 41384-41392.

U. S. Fish and Wildlife Service. 1998. "Recovery Plan for Vernal Pools of Southern California." U.S. Fish and Wildlife Service. Portland. 160 pp.