|Listed||September 28, 1978|
|Description||Decumbent annual grass.|
|Habitat||Prairie; sandy patches in vernal ponds.|
|Threats||Low numbers, livestock, collectors.|
Solano grass, Tuctoria mucronata, is an annual grass, 0.8-8 in (2-20.3 cm) tall. Stems grow decumbently from the base of the plant, trailing its base stems along the ground. Rigid, curved leaf blades are covered with small drops of an acrid sticky secretion that is characteristic of its genus. The yellow-green flowers extend in clusters and grow out of a central stem with stamens and pistols contained within the sheath of the petal.
Seeds germinate in May or June as water levels recede, and plants grow quickly while there is still moisture. Plants begin flowering in mid-July; the flower is wind pollinated and remains partially enclosed by the upper leaf sheath. This species has also been known by the scientific name Orcuttia mucronata.
The Jepson Prairie is a unique habitat of central California that is known for its vernal pools, a vernal lake, and remnant stands of prairie plants. The bed of the vernal Olcott Lake contains shallow spots, scoured by waves during the winter months, which dry into uniform white and sandy textured surfaces in the spring and summer. In deeper-lying areas, shallow pools persist for many weeks after the lake begins drying out in the spring. As water evaporates, the clay sediment dries into a thin crusty film, later forming a web of cracks. Solano grass grows in these cracks.
Solano grass was discovered in 1958 at Olcott Lake, north and east of Fairfield, California. Before the area was developed for agriculture, Solano grass was more widely distributed. It grew throughout the flooded areas behind low natural levees along the waterways that drain the Sacramento Valley. Solano grass is known only from the western portion of Olcott Lake. In 1982, 53 plants were counted. Other large pools west of Olcott Lake have not yet been surveyed for the plant.
The habitat of Solano grass has declined overall because of conversion of land to agriculture. Cattle, horses, and sheep use Olcott Lake for grazing and watering, especially in late spring when Solano grass germinates. In 1981, the Nature Conservancy, which owns the Jepson Prairie Preserve in the northwest quadrant of Olcott Lake, removed grazing horses from the lakebed. The following year more than 50 plants were found in that part of the lake, suggesting that disturbance by livestock may be a major factor in the decline of Solano grass. Specimen collection may also have reduced the population of this species. The formerly pristine condition of the Jepson Prairie Preserve made it a favorite study site for researchers and classes from several local colleges and the University of California. The Nature Conservancy now requires that people using the Jepson Prairie Preserve refrain from collection of any grasses growing below the high water line of Olcott Lake.
Conservation and Recovery
The Nature Conservancy reached an agreement with the University of California Natural Land and Water Reserves System for joint management of the Jepson Prairie Preserve. The University of California, Davis Campus, is charged with day-to-day oversight of the preserve. If at least three populations of the grass can be established and maintained in other protected vernal lakes within the region for at least 15 years, then the species will be considered for delisting.
U.S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
Eastside Federal Complex
911 N. E. 11th Ave.
Portland, Oregon 97232-4181
Telephone: (503) 231-6121
Crampton, B. 1959. "The Grass Genera Orcuttia andNeostapfia : A Study in Habitat and Morphological Specialization." Madroño 15: 97-110.