Goal: Protect, enhance, and restore Otay mesa mint occupied and historically occupied habitat to create self-sustaining populations that are resilient to environmental stochasticity and threats, such as altered hydrology, climate change and invasive plants, and will be likely to persist over the long-term (>100 years).
Management units: 3
Beginning in 2018, conduct annual surveys for Otay mesa mint in occupied, historically occupied and potentially suitable vernal pools to determine cover clases in each basin and cover of each nonnative species using a standardize protocol as defined in the VPMMP (City of San Diego 2015). Nonnative cover classes will be combined to determine if management triggers for Level 1, 2 or 3 management are met. Management recommendations will be made, noting individual nonnative species that pose a threat to direct specific management actions. Management actions will be implemented annually as part of the general vernal pool habitat management objectives for different management levels (ML1, ML2, ML3).
|IMP-1||Submit project metadata, monitoring datasets and management recommendations to the MSP Web Portal.||On hold|
|Annual Surveys Completed with Management Recommendations||2021|
|Threat Name||Threat Code|
|Human uses of the Preserves||HUMUSE|
Otay Mesa Rare Plants
The Otay Mesa Rare Plants Project will improve the conservation status of several of San Diego County's rarest plants on important conserved lands in Otay Mesa. The Project includes seed bulking for two high-priority Management Strategic Plan (MSP) plant species and direct restoration of five MSP plants with seeding, planting, and maintenance. Seeding, planting, and maintenance for the MSP plants will be conducted as part of two separate habitat restoration projects, one to restore vernal pools and maritime succulent scrub and another to restore maritime succulent scrub and native grasslands.
|File name||Lead Author||Year||Type|
|County of San Diego MSCP Monitoring Summary Report January 1998 - June 2007||County of San Diego||2007||report|
|MSP Roadmap Dec 31, 2016: VF Species and Vegetation Goals, Objectives, and Actions||San Diego Management and Monitoring Program||2016||other|
|Otay Mesa Rare Plants Final Report||2022||report|
|Revised Final City of San Diego Vernal Pool Habitat Conservation Plan Management and Monitoring Plan||2020||report|
|Summary Results of Rare Plant Field Monitoring City of San Diego MSCP||2009||fact sheet|
|Transnet Environmental Mitigation Program Grant Agreement #5001761; Final Report for the San Diego National Wildlife Refuge Vernal Pool Invasive Weed Control Project||Terp, Jill||2015||report|
|Vernal Pool Management and Monitoring 2019||Berninger, Mark||2019||powerpoint presentation|
|Vernal Pool Restoration Final Report||2018||report|
|Weed Control on the Vernal Pool Restoration Areas of the San Diego National Wildlife Refuge: Jamul, California||2013||report|
Restricted to vernal pools on Otay Mesa in southern San Diego County, California . Historically, known across the international border where the Tijuana International Airport is now located. No Tijuana populations of Pogogyne nudiuscula are known to exist today .
Within MSPA, it is found in MU3 at three locations on Otay Mesa: Otay Mesa West, Otay Mesa East, and Otay Mesa Northeast .
An obligate vernal pool species occurring only on Stockpen soils in Southern coastal mesa vernal pools ; 90-250 m in elevation . Considered an obligate wetland species (found almost always in wetland areas), but is more tolerant of the ephemeral inundation of vernal pool habitat than true wetland plants .
Mint family (Lamiaceae) . One of 8 recognized species of Pogogyne . John Thomas Howell (1931) separated Pogogyne nudiuscula into two species: Pogogyne nudiuscula and Pogogyne abramsii; based on differences in the calyx pubescence (hairiness), bract morphology, and the number of flowers per stem node . Recent work suggests that P. nudiuscula was not known to occur north of Otay Mesa . A population of Pogogyne in Baja California, Mexico, which was considered P. nudiuscula has been found to be a unique species based on the calyx to corolla ratio, the number of flowers per node, and the general size of the floral parts [5, 6].
An annual herb reaching 9-30 cm (1 foot) in height and flowers arranged in whorls . The plants usually give off a strong, turpentine mint odor . Bracts are green with acute tips . Leaves are spatulate, obtuse and subglabrous approximately 1 to 2 cm long with short petioles (stalks) . Stem erect, stout, often 0.8–1 mm diam at inflorescence base. Inflorescence 10–20 mm wide; calyx glabrous to sparsely hairy, corolla 11–14 mm, style hairy 1.5–4 mm below stigma lobes. Fruit ± 1.5 mm .
Blooms from May or June through early July when water is absent from the vernal pool, completing its life cycle in the spring rather than in the summer through winter months . The sparsely hairy, small bell-shaped purple flowers have a white throat and diagnostic hairy style . It has at least six flowers per node on the stem . The link between the onset of germination, the temporal conditions needed for vernal pool inundation, temperature, and moisture are critical to the germination, maturation, flowering, and fruiting of P. nudiuscula .
Vernal pool populations receive pollination services from generalist bees typically in the family Apidae . Potential pollinators in nearby chaparral were also found visiting vernal pool flora . Native sweat bees (Lasioglossum spp.) and bee flies (Bombyliidae) are the most common pollinators [10,11]. Research on Pogogyne abramsii shows that it is self-fertile but has greater seed set when cross-pollinated; further research is necessary to determine if this is the case for P. nudiuscula [4,12]. Small animal movement may be a potential vector for seed dispersal and gene flow between vernal pool obligate species .
Threatened by habitat loss and degradation due to filling, grading, discing, leveling, urban and agricultural development, road projects, grazing, off-road vehicle use, trampling, invasion from weedy nonnative plants, trash dumping, soil compaction, erosion, drought, habitat fragmentation and isolation of vernal pool systems and complexes, and alteration of the watershed . Destruction of watersheds and disruption of hydrological systems can create further impacts by creating barriers to dispersal, such that pollination and reproductive output may be inhibited .
P. nudiuscula has specific habitat requirements (e.g., soil type/Stockpen soils, water depth) therefore, habitat degradation and alteration of the surrounding habitat will likely result in a population decline or even local extirpation . Natural differences in the precipitation and the inundation/drying time of the vernal pool from year to year may result in significant differences in P. nudiuscula distribution and abundance, making it difficult to obtain an accurate measure of the population . In addition, a portion of the population is represented by seeds remaining in the seed bank and is not accounted for in each survey year . Modifications to the uplands surrounding a vernal pool complex can impact the pool’s hydrology, even if they occur outside the pool’s surface area . P. nudiuscula occurrences on Otay Mesa are in areas that experience a high volume of foot traffic between Mexico and the United States . Increased border security on Otay Mesa may threaten vernal pool habitat along the international border. Because P. nudiuscula is dependent on the timing and length of inundation, alterations to vernal pool complexes may inhibit establishment or adversely impact the long term viability of vernal pool plant populations [5,14]. Protection of suitable habitat and restoration of vernal pool habitat may help to expand P. nudiuscula’s range and help reduce the impacts associated with small populations and a restricted range .
 California Native Plant Society Rare Plant Program. 2016. Inventory of Rare and Endangered Plants (online edition, v8-02). California Native Plant Society, Sacramento, CA. Available: http://www.rareplants.cnps.org. Accessed November 8, 2016.
 U.S. Fish and Wildlife Service. 1998. Vernal Pools of Southern California Recovery Plan. Portland, OR.
 MSP-MOM. 2014. Management Strategic Plan Master Occurrence Matrix. San Diego, CA. Available: http://sdmmp.com/reports_and_products/Reports_Products_MainPage.aspx
 U.S. Fish and Wildlife Service. 1993. Determination of Endangered Status for Three Vernal Pool Plants and the Riverside Fairy Shrimp. Federal Register 58: 41384–41392.
 U.S. Fish and Wildlife Service. 2010. Pogogyne nudiscula (Otay Mesa Mint) 5-Year Review: Summary and Evaluation. Carlsbad, CA.
 Silveira, M., M.G. Simpson, J.D. Jokerst. 2016. Pogogyne nudiuscula, in Jepson Flora Project (eds.) Jepson eFlora. Available: http://ucjeps.berkeley.edu/cgi-bin/get_IJM.pl?tid=38938. Accessed December 20, 2016.
 Jokerst, J.D. 1993. The Jepson Manual: Higher Plants of California, Pogogyne, ed. J.C. Hickman. Berkeley: University of California Press.
 Munz, P.A. 1974. A Flora of Southern California. Berkeley: University of California Press.
 Scioli, J.A. 2014. Pollinator Specificity and Pollen Limitation in the San Diego Mesa Mint, Pogogyne abramsii, A Vernal Pool Endemic. University of California, San Diego.
 Thorp, R.W. & J.M. Leong. 1998. Specialist Bee Pollinators of Showy Vernal Pool Flowers, ed. C.W. Witham et al.,169-179, Ecology, conservation and management of vernal pool ecosystems- Proceedings from a 1996 conference. California Native Plant Society, Sacramento, CA.
 Schiller, J. R., P. H. Zedier, and C. H. Black. 2000. The Effect of Density Dependent Insect Visits, Flowering Phenology, and Plant Size on Seed Set of the Endangered Vernal Pool Plant Pogogyne abramsii (Lamiaceae) in Natural Compared to Created Vernal Pools. Wetlands 20: 386– 396.
 Zedler, P.H. 1987. The Ecology of Southern California Vernal Pools: A Community Profile. Biological Report 85 (7.11). U.S. Fish and Wildlife Service, Washington, DC.
 Zedler, P.H. and C. Black. 1992. Seed Dispersal by a Generalized Herbivore: Rabbits as Dispersal Vectors in a Semiarid California Vernal Pool Landscape. American Midland Naturalist 128:1– 10.
 Bauder, E.T. 1987. Threats to San Diego Vernal Pools and Case Study in Altered Pool Hydrology, ed. T.S. Elias, 209-213, Conservation and Management of Rare and Endangered Plants. Proceedings from a conference of the California Native Plant Society.