Acanthomintha duttonii

San mateo thornmint, San Mateo thorn-mint, San Mateo thorn-mint

Family: Lamiaceae · Type: annual · Native

Conservation status: CNPS 1B.1 · Endangered

San mateo thornmint is a rare (CNPS 1B.1) California native annual found in the Central Coast and San Francisco Bay Area bioregions, specifically in San Mateo County, in serpentine grassland habitats at elevations below 300 meters. Flowering from April to June, this plant produces white to lavender flowers with distinctive pink-red anthers, approximately 12 to 16 millimeters long. Growing with slender, generally unbranched stems less than 20 centimeters tall, it forms compact clusters with minimal branching. Its lance-oblong to obovate leaves measure 8 to 12 millimeters long, with margins occasionally serrate and without spiny edges. The plant's inflorescence features distinctive bracts 5 to 11 millimeters long with 5, 7, or 9 marginal spines measuring 3 to 7 millimeters.

Habitat: Serpentine grassland

Bloom period: Apr-Jun

Elevation: < 300 m

Bioregions: CCo, SnFrB (San Mateo Co.).

California counties: San Mateo

Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, Jepson eFlora, Cal-IPC, and more.