Jared's peppergrass

Lepidium jaredii is a mustardlike annual herb growing slender, erect stems up to about 70 centimeters in maximum height. The leaves are lance-shaped and up to 10 centimeters long. There are two subspecies of the plant; ssp. jaredii, Jared's or Carrizo pepperweed, has yellow petals, whereas ssp. album, Panoche pepperweed, has white petals. Subspecies album is validly published, but not currently recognized in Jepson Manual 2. The species appears to have a strict edaphic affinity for clay soils and particularly those with substantial gypsum and salt accumulation in the lower soil profile. For soils of ssp. album, the parent material is typically a marine shale, especially the Moreno shale formation. This soil is an extreme substrate type in which Lepidium jaredii typically dominates, relatively free of competition with other plant species. The soil is typically 3 to 5 inches of high shrink-swell clay topsoil (smectite clay; hard, cloddy when dry) over several inches of subsoil enriched in precipitated gypsum and salts (powdery when dry). The pH of the soils is typically very acidic (as low as 4.5). Lepidium jaredii is of conservation concern as both ssp. jaredii and ssp. album have limited ranges. …