Colusa Grass
See  photo info below

Sacramento Fish & Wildlife Office
Species Account

COLUSA GRASS
(Neostapfia colusana)

CLASSIFICATION: Federal Threatened Species (Federal Register 62:14338; March 26, 1997)

This species was listed as endangered by the California Department of Fish and Game in November 1978. The California Native Plant Society has placed it on List 1B (rare or endangered throughout its range).

CRITICAL HABITAT: Originally designated in Federal Register 68:46683 pdf; August 6, 2003.

The designation was revised in 70:46923 pdf; August 11, 2005.

Species by unit designations were published in 71:7117 | PDF February 10, 2006.

RECOVERY PLAN: Recovery Plan for Vernal Pool Ecosystems of California and Southern Oregon

DESCRIPTION:

Colusa grass (Neostapfia colusana) is a robust, tufted annual in the grass family (Poaceae) that grows 3-12 inches tall. The lower portions of the stems lie on the ground; the upper portions are erect and terminate in dense cylindrical, spike-like inflorescences that superficially resemble small ears of corn. The inflorescence and overall appearance of the plant are unique, so this species is not easily confused with any other. See Hickman (1993) in General Information about California Plants, below, for a detailed description.

Colusa grass is the only species in the genus Neostapfia. The closest relatives of this species are the Orcutt grasses.

DISTRIBUTION:

Colusa grass occurs in large or deep vernal pools with substrates of high mud content. It is sparingly restricted to the Sacramento and San Joaquin Valleys.

Currently, no more than 45 occurrences of Neostapfia colusana remain extant. The majority of the extant occurrences are in the southern Sierra Foothills, where they are concentrated northeast of the City of Merced in Merced County and east of Hickman in Stanislaus County.

Four occurrences are extant in the Solano-Colusa region. There are two each in southeastern Yolo and central Solano Counties. The species has apparently been extirpated from Colusa County.

See distribution map from the draft recovery plan.

THREATS:

Habitat loss and fragmentation are the largest threats to the survival and recovery of vernal pool species. Loss of habitat generally results from urbanization, agricultural conversion and mining.

Habitat loss also occurs in the form of habitat alteration and degradation as a result of changes to natural hydrology, invasive species, incompatible grazing regimes, infrastructure projects (e.g., roads, water storage and conveyance, utilities), recreational activities (e.g., off-highway vehicles and hiking), erosion, contamination and inadequate management and monitoring.

Additional specific threats to Neostapfia colusana include inundation by poultry manure, damage by herbicide applications, and groundwater becoming contaminated by industrial chemicals.

Almost all of the extant occurrences colusana are subject to livestock grazing. To the extent inappropriate grazing practices are still being followed at certain sites, these sites may be threatened.

Competition from invasive native and non-native plants poses a problem at several sites, especially in combination with adverse hydrology changes and adverse grazing practices. Appropriate grazing can be a valuable component of invasive species control.

REFERENCES FOR ADDITIONAL INFORMATION:

General Information about California Plants

Photo of Colusa grass by Rick York, © 1982 California Native Plant Society, Calphoto ID: 0000 0000 0502 1166

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