Endangered Species Recovery Program
None federal or state. California Native Plant Society List 1A.
Diamond-petaled California poppy has been seen so infrequently that little is known about the species. It is an annual. Flowering specimens were collected in March and April. At one site, this species was found on nearly barren areas of clay soils in association with San Benito thornmint (Acanthomintha obovata) and large-leaved filaree (Erodium macrophyllum). Diamond-petaled California poppy also has been found in fallow fields. Historical locations ranged from 9 to 1,000 m in elevation.
Diamond-petaled California poppy has finely divided basal leaves with fleshy bases. The entire plant is hairless. The flowers have four small, yellow petals but do not have a rim-like appendage below the petals. Diamond-petaled California poppy has cylindrical fruits that may nearly equal the height of the plant.
Diamond-petaled California poppy was known historically from seven sites in the inner Coast Ranges of Alameda, Colusa, Contra Costa, San Luis Obispo, and Stanislaus counties. Although natural land remains in most of the areas where it was collected historically, it has not been observed at any of those sites since 1950. Urban development and agriculture have eliminated habitat at a few sites. The only population of diamond-petaled California poppy known to be extant is at the Lawrence Livermore National Laboratory in Alameda County, where it was discovered in 1997.
Subclass MAGNOLIIDAE, Order PAPAVERALES, Family PAPAVERACEAE, Genus Eschscholzia, Species rhombipetala
Eschscholzia caespitosa var. rhombipetala
Skinner, M.W., and B.M. Pavlik, eds. 1994. Inventory of rare and endangered vascular plants of California. Fifth edition. Spec. Publ. No. 1, California Native Plant Society, Sacramento, 338 pp.; Clark, C. 1993. Papaveraceae. Pp. 810-816 in The Jepson manual: higher plants of California (J.C. Hickman, ed.). University of California Press, Berkeley, 1400 pp.; Hoover, R.F. 1970. The vascular plants of San Luis Obispo County, California. University of California Press, Berkeley, 350 pp.; Rarefind, California Natural Diversity Data Base, Sacramento.
3-15 mm long
4B7 cm long
1.3-1.8 mm wide
Among poppies in the same genus, fleshy leaf bases are unique to diamond-petaled California poppy. Tejon poppy (E. lemmonii ssp. kernensis) [CL] and Lemmon's poppy (E. lemmonii ssp. lemmonii) have larger, deeper orange flowers than diamond-petaled California poppy. California poppy (E. californica) not only has larger flowers than diamond-petaled California poppy but also has a conspicuous rim-like appendage below the petals. Frying pans (E. lobbii) differs from diamond-petaled California poppy in leaf position and seed characteristics.