ChapterMtg-2015-10-1ChapterMtg-2015-10-2Monolopia major (cupped monolopia) on hillside; phot by Ryan O’DellCalifornia contains a rich diversity of edaphic (soil-influenced) endemic plant species, including those restricted to physically and chemically extreme substrates such as serpentine, gabbro, carbonate, gypsum, and clay. Vertic clay soils present a unique extreme stress to plant growth due to extreme swelling and shrinking with seasonal wetting and drying cycles, resulting in formation of deep soil cracks that rip roots. Vertic clay soils derived from gypsum-rich shale have exceedingly low pH (< 5) and often contain high bioavailable concentrations of selenium.
Numerous California Rare Plant Rank (CRPR) species are endemic to the vertic clay soils of the Inner South Coast Ranges (Corral Hollow to Carrizo Plain). Species include Madia radiata (CRPR 1B.1), Deinandra halliana (1B.1), Monolopia major, Lepidium jaredii ssp. album (1B.2), Convolvulus simulans (4.2), Allium howellii var. sanbenitense, Caulanthus flavescens, California macrophylla (1B.1), Acanthomintha obovata ssp. obovata (4.2), Benitoa occidentalis (4.3), Fritillaria agrestis (4.2), Lagophylla diabolensis (1B.2), and Eriogonum argillosum (4.3). Most of these species occur in arid climates and flower early (mid-February to mid-April). Premier locations to view Inner South Coast Ranges vertic clay endemic plant species include Corral Hollow Road (eastern Alameda), BLM Panoche Hills and Tumey Hills (western Fresno County), Coalinga Road (southern San Benito County), and Carrizo Plain-Temblor Mountains (eastern San Luis Obispo-western Kern Counties).

The focus of Ryan’s talk will be primarily on the characteristics of the vertic soils as an extreme, low-competition habitat and the rare plants that grow there. These species don’t appear to form consistent communities. There are some subtle species associations with slope gradient and aspect. Very little is known about the adaptations of these species to the vertic soil condition. He will speculate on what the adaptations may be, but verification of those adaptations will be left to future research.

Ryan O’Dell is a Natural Resource Specialist (Botany/Soils/Paleontology) with the Bureau of Land Management in Hollister, California. His specialty is edaphic endemic plant species ecology and conservation.