Acanthomintha ilicifolia A.Gray

San Diego thorn-mint is an endemic species on the mesas and foothills of San Diego County and northern Baja California. San Diego thorn-mint occurs in open areas, clay depressions and vernal pools within chaparral, coastal sage scrub and annual grassland habitats below 2,953 feet (900 m) elevation [15,23,31]. San Diego thorn-mint is often associated with clay soils derived from gabbroic rock, which is uncommon in San Diego County and contributes to San Diego thorn-mint's rarity. Plants typically occur on gentle slopes of 15 to 20 degrees [32].

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: 21 - 80

Comments: Thirty-two occurrences extant in United States and at least 9 in Mexico known to have recently had the species. Twenty extirpated/historical in United States (U.S. Fish and Wildlife Service 1998). 52 occurrences presumed extant in 2010 but many may actually be extirpated.

Global Range: Only known from coastal San Diego County, California and adjacent Baja California Norte, Mexico.

Rounded Global Status Rank: G2 - Imperiled

Reasons: Acanthomintha ilicifolia is know from 32 extant occurrences in coastal San Diego County, California, and at least 9 occurrences in Baja California Norte, Mexico (Sierra Juarez and coastal). There are approximately 150,000-170,000 individuals in the U.S., but only 4 of the occurrences are major. The others are small, and all are isolated by surrounding extensive urban and agricultural development. Habitat loss and fragmentation are expected to continue with the development of southern California and northern Baja California. At least 40% of the historic known sites in the U.S. have been extirpated by residential and commercial development. Ongoing off-road vehicle use, trampling by cattle, erosion, and invasion by non-native plants are also threatening populations.