Few-Flowered Navarretia

(Navarretia leucocephala ssp. pauciflora)

Few-flowered navarretia (Navarretia leucocephala ssp. pauciflora) is a California threatened plant species, which means that killing or possessing the plant is prohibited by the California Endangered Species Act (CESA). Few-flowered navarretia is also listed as endangered under the federal Endangered Species Act. Few-flowered navarretia is a small annual herb that forms in mats and produces small pale blue or white flower heads that typically appear from May to June. There are usually two to twenty flower heads, about half that of the closely related subspecies many-flowered navarretia (Navarretia leucocephala ssp. plieantha). Few-flowered navarretia is a vernal pool plant, and is found only in these unique wetlands. The species is included in the Recovery Plan for Vernal Pool Ecosystems of California and Southern Oregon (PDF) (Recovery Plan) completed by the U.S. Fish and Wildlife Service in 2005.

At the time of this webpage posting, the California Natural Diversity Database lists ten occurrences of few-flowered navarretia that are presumed to still exist; however the survey data for these occurrences has not been recently updated. One of these occurrences is at Loch Lomond Vernal Pool Ecological Reserve, owned by CDFW, and one is at Mead Ranch, which is protected from development by a conservation easement held by the Napa Valley Land Trust. The remaining eight occurrences are on privately-owned land and are not protected.

Like other vernal pool species, the biggest threat to few-flowered navarretia is habitat loss and fragmentation due to agriculture and development. Development can result in direct removal of vernal pool habitat as well as indirect consequences such as altered hydrology, runoff, invasive species encroachment, and groundwater contamination. Climate change is also a threat to vernal pool species. According to the Recovery Plan, threats specific to few-flowered navarretia include disturbance of volcanic ash soil, erosion, off-road vehicles, land-use conversions, grazing, and reduction of pollinators.

Occurrences of few-flowered navarretia on privately-owned land should be protected through conservation easements or other means. A Draft Management Plan for the Loch Lomond Vernal Pool Ecological Reserve (PDF) has been prepared and should be implemented, and management plans should be written and implemented for the other occurrences on publicly-owned land. Surveys should be conducted at all occurrences to determine the current status of the species. Additionally, research should be conducted on the genetic structure and taxonomic status of few-flowered navarretia and its related subspecies. Potential habitat should be surveyed, and if new populations are located, they should be protected. Recommended actions to help vernal pool species in general can also be found in the Recovery Plan.