Sacramento Orcutt Grass

The Sacramento Orcutt grass is only found in a narrow zone of eastern Sacramento County at the base of the Sierra Nevada foothills. It only grows in vernal pools with Northern Hardpan and Northern Volcanic Mudflow soils located between 150 to 270 feet in elevation. Sacramento Orcutt grass is known from 12 locations in eastern Sacramento County, but two populations no longer exist. Of the 10 remaining populations, eight are protected and there have been several successful projects to introduce the species to protected vernal pools within eastern Sacramento County. 

Sacramento Orcutt grass looks different during each of its life stages. Seeds are very small and oval. Plants in the aquatic phase are small and inconspicuous and have stems that lie flat or are supported by the water during this time. Leaves that form during the aquatic life stage are cylindrical and clustered into a small rosette. As vernal pools dry, Sacramento Orcutt grass plants becomes terrestrial. In its terrestrial stage, Sacramento Orcutt grass is a small plant that grows 1 to 4 inches tall. Unlike most grasses, Sacramento Orcutt stems are filled pith, which is a soft and spongy center found in many flowering plants. Each plant may have multiple slender upright stems crowned with a spike of densely grouped tufts. Sacramento Orcutt grass has tiny white flowers that have five petals with the middle petal being longer than lateral petals. The cylindrical leaves of the aquatic life stage transform into flattened blades and are distributed along the stem during the terrestrial life stage. The stems and leaves are covered with small hairs that secrete a sticky substance. The stickiness increases as the plant matures and likely helps repel herbivores. Like other Orcutt grasses, the leaves lack a ligule, or a small outgrowth found at the junction of leaf and leafstalk on some grasses.

Measurements
Seed length: 2.5 mm
Height: 1 to 4 in

Sacramento Orcutt grass is an annual plant with three distinct life stages. Each rainy season, seeds from previous years sprout and begin to grow underwater, between November and January, as the rains fill vernal pools. During the aquatic life stage, Sacramento Orcutt grass can be very difficult to find. As the pools dry, plants enter their terrestrial life stage. At this time, the grass can be seen within the vernal pool bottom through July and August. The grass blooms in the terrestrial life stage in May and June. The grass is thought to be wind pollinated like other Orcutt grasses for seed development. 

Seeds are the final life stage of Sacramento Orcutt grass. The seeds usually form after pollination in May through July and fall close to the plant upon maturity. Plants die after the seeds mature. Most seeds travel no more than a few inches away from the parent plant. The seeds may remain dormant in the soil for several years until there is enough water in the vernal pools for the seeds to sprout.