Robinson Pepper-grass [Lepidium virginicum L. var. robinsonii (Thell.) Hitchc.]

Robinson Pepper-grass [Lepidium virginicum L. var. robinsonii (Thell.) Hitchc.]

Listing CNPS List 1B R-E-D Code 3-2-2

State/Federal. Status -- None BRASSICACEAE Jan.-Jul.

Global Rank G5T2T3 State Rank S2?

Distribution: San Diego County, Riverside County, Orange County, Los Angeles County, San Bernardino County, Santa Barbara County, Santa Cruz Island; Baja California, Mexico

Habitat: This annual herb grows in openings in chaparral and sage scrub, generally well away from the coast in Southern California in the foothill elevations. Typically sites where this species is observed are relatively dry, exposed locales, rather than beneath a shrub canopy or along creeks.

Known Sites: This pepper-grass is locally common in the San Vicente Reservoir region on the periphery of the coastal plain. Herbarium specimens examined from elsewhere in San Diego County are from Otay Lake, Tecate Junction, Rancho Santa Fe, north of the Scripps Institute in an area that includes a number of typically more inland elements, the San Luis Rey Valley, Federal Boulevard near Emerald Hills in San Diego, Whispering Oaks near the Sloane Ranch, Florida Street near Balboa Park in San Diego, Harbison Canyon, the Ryan Oak Glen Preserve northeast of Escondido, and near the county line and U.S. 395. An isolated, but fairly vigorous population was observed on the hill east of Massachusetts Avenue and north of Freeway 94 in La Mesa. Roberts reports this species in his Orange County checklist; Boyd reports it lightly distributed throughout the Gavilan Hills of western Riverside County. Smith reports variety robinsonii from Pelican Harbor on Santa Cruz Island.

Five specimens from Baja California are found at the herbarium of the San Diego Natural History Museum, south to 30 20' North where collected by Moran (SD 127352).

Status: Robinson Pepper-grass is presumed stable in Southern California. This small annual was recently listed by the CNPS; however, it is likely more common than presumed by the R-E-D Code assigned to it. This species sometimes replaces both Lepidium nitidum and Lepidium lasiocarpum in the sage scrub and chaparral understory as the coastal plains give way to the foothills of southern San Diego County. Chamise Chaparral and a xeric sage scrub occupy most of this foothill zone, and it is an area which has not historically been intensively collected by botanists due to the paucity of endemic plants and distinctive microhabitats. A similar situation may occur on the western flanks of the San Jacinto Mountains of western Riverside County. Provisionally, protection is only recommended for portions of sizeable populations. This annual differs from L. lasiocarpum by its relatively round (not flattened and hairy pedicels) which are often longer than the fruit; leaves are toothed unlike L. nitidum.

Copyright May 1994 Craig H. Reiser.

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