Nassella; Photo by Ellen DeanLarge areas of blue oak woodland and open grassland are covered with well-established individuals of three species of needlegrass, Nassella pulchra, N. cernua, and N. lepida. Cool, damp, north-facing slopes under interior live and black oaks support luxuriant stands of fescue (Festuca californica and F. idahoensis). California melic and blue wildrye (Elymus glaucus) thrive in slightly mesic areas with overstory trees. Many native forbs also thrive in the grasslands of the Reserve, often offering spectacular spring displays of lupines (Lupinus nanus).

As in nearly all of California, much of the grassland is either dominated by or has a significant proportion of exotic annual grasses. Bromes (Bromus diandrus, B. hordeaceus, and B. madritensis) and wild oats (Avena fatua) comprise the majority of the exotic grass biomass, but there has been recent encroachment by aggressive Lupinus nanus; Photo by Dan Tolsonand problematic grasses such as medusahead (Taeniatherum caput-medusae) and barbed goatgrass (Aegilops triuncialis). In addition to the native forbs, the grasslands also include many non-native dicots such as filaree (Erodium cicutarium), burclover (Medicago polymorpha), and yellow starthistle (Centaurea solstitialis).

The majority of the areas of grasslands that appear on the vegetation map occur on south- and west-facing slopes. Some are adjacent to chaparral, and some appear within woodland areas where the tree cover decreases. The California Annual Grasslands Alliance covers only 1.0% of the Reserve. Only one small area on the Reserve, which was bulldozed during the 1992 fire, appears as the weedier “Upland Annual Grasses” community on the vegetation map. This community covers less than 0.01% of the Reserve.Yellow starthistle; Photo by Shane Waddell

Over the past 10 years, the Reserve staff has actively controlled goat grass, medusahead, and yellow starthistle with herbicides. Many, but by no means all, of the recent invasions by these species have occurred along roadsides, making populations both visible and treatable. Populations in the steep, remote portions of the Reserve will be much harder to control, but offer some evidence of whether control measures are necessary.

There is a small area of Wet Meadow Grasses Superalliance on Bureau of Reclamation land east of the Reserve. This is probably associated with an artificial pond adjacent to a creek bottom.

Photo Credits: Title, Ribes malvaceum (Dan Tolson), Nassella (Ellen Dean), Lupinus nanus (Dan Tolson), Yellow starthistle, (Shane Waddell). For more pictures see:

This page last updated: March 15, 2016  

Contact: Dr. Virginia Boucher
John Muir Institute of the Environment
109 The Barn, University of California, Davis, CA 95616
Phone: 530-752-6949; email:

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