Otay Mesa Mint [Pogogyne nudiuscula Gray]

Otay Mesa Mint [Pogogyne nudiuscula Gray]

Listing CNPS List 1B R-E-D Code 3-3-2

State/Federal. Status -- CE/FE LAMIACEAE May-Jun.

Global Rank G1 State Rank S1.1

Distribution: Otay Mesa; northern Baja California, Mexico

Habitat: This small annual is restricted to Vernal Pools. Stockpen gravelly clay loam is the preferred soil type. While some Chamise Chaparral is associated with Otay Mesa Mint in the extreme northeastern corner of Otay Mesa, most of the colonies occur in open grasslands with Mima Mound topography. Both Brodiaea orcuttii and Muilla clevelandii are often associated with this species. A portion of the very limited range of this plant, east of Brown Field, was once a bombing range. A very few of the craters which resulted are interspersed with the vernal pool system, and may occasionally harbor vernal pool elements.

Known Sites: This mint is reported in the small Pool J14 which is within the alignment route of the proposed Interstate 905. It is growing in the J23-J25 and J29-30 pools east of Brown Field which are being utilized as cow wallows and are cumulatively being degraded and rendered unsuitable as habitat. The somewhat more protected J26 Pools on northeastern Otay Mesa possess the only healthy, well-protected, and vigorous populations. A recent, relatively thorough vernal pool report of this region found Loma Alta Mint in 17 pools from the J29-30 Series, 24 pools in the J23-24 Series, and 55 pools in the J25 Series. Most sites are now threatened by urban development, particularly from the construction/expansion of new jails/prisons nearby. No other extant populations are known for this species. Old reported collection sites where no longer extant are from Mission Valley in the 1890's and a June 1930 specimen from Adobe Falls. The former pools which once occurred near San Diego State University may have had populations of this annual. Data Base reports cover the locales already mentioned; a site it mentions near the El Camino Memorial Park is a likely misidentification of P. abramsii.

Only five specimens from Baja California are found at the San Diego Natural History Museum's herbarium. Sites near the Tijuana Airport may be recently extirpated; this facility is continually being expanded for international travel.

Status: The Otay Mesa Mint is close to extinction. It is much rarer than the San Diego Mesa Mint, which also has Federal Endangered status. Most known sites are imperiled by development. This is one of San Diego County's most endangered species. Airport expansion at Brown Field to the east could seriously impact this species. Free ranging cattle grazing is a severe problem on Otay Mesa. All populations should be fully protected with adequate buffers.

Copyright May 1994 Craig H. Reiser.

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