|Dutton's acanthomintha, San Mateo thornmint|
The following Participating Institutions are custodians for this species in the CPC National Collection:
University of California Botanical Garden
The conservation of Acanthomintha duttonii is fully sponsored.
Holly Forbes contributed to this Plant Profile.
San Mateo thornmint is found only in serpentine grassland in a small area south of San Francisco, in San Mateo County, California. This annual herb grows erect up to 20 cm. tall; its leaves are 8-12 mm. long, usually with toothed margins. Bracts in the inflorescence have marginal spines and the flowers are white, sometimes tinged with purple. This species is known from only one naturally occurring, fragmented population. The larger fragment occurs on county park land; the smaller fragment, with fewer than 50 plants, is on adjacent land owned by the San Francisco Water Department. Historically, the species was scattered infrequently throughout this area, but most populations (three known) were destroyed by urban and associated highway development.
Distribution & Occurrence
This species grows on open substrate on mesic grassland slopes in soils derived from serpentine rock at elevations below 300 m. It grows in a species-rich forb association, including Nasella pulchra, Lolium multiflorum, Delphinium hesperium, and Hemizonia congesta var. luzulifolia (Pavlik and Espeland 1998).
|The numbers of this annual herb vary by year, from over 53,000 in 1994 to a low of 5,289 in 1997 (Pavlik and Espeland 1998).|
Conservation, Ecology & Research
Potential change in local environmental conditions from nearby development disturbance by hikers and mountain bikers.
Seeds were put into long-term storage at the National Seed Storage Laboratory in 1988 and another collection will be made in 2002 in collaboration with the U.S. Fish & Wildlife Service.
Nearby fencing helps restrict unauthorized vehicular access.
Thomas, J.H. 1961. Flora of the Santa Cruz Mountains of California. Stanford, California: Stanford University Press.