Gilia tenuiflora ssp. arenaria
|Listed||June 22, 1992|
|Description||Annual herb with rosettes, narrow petals and narrow purple throat on funnel-shaped flowers.|
|Habitat||Coastal foredunes and coastal dunescrub communities.|
|Threats||Invasion of alien plants, proposed commercial and residential development, off-road vehicle damage.|
The Monterey gilia, Gilia tenuiflora ssp. arenaria, is an erect short rosette-forming, annual herb, usually less than 6.7 in (17 cm) tall. The narrow petals and narrow purple throat of the funnel-shaped flower, the open inflorescence, the short fruits or capsules measuring 0.13-0.2 in (3.5-5.0 mm), and the slightly exerted stamens separate this subspecies from the other G. tenuiflora subspecies.
The species is thought to be primarily self-pollinating based on its stamens not protruding from the flower, no observations of pollinators, and very viable seed. Seeds in the field germinate from December to February, and fruit is set from the end of April to the end of May. Seeds are dispersed by wind through the dune openings, but dispersal is inhibited by dense stands of low-growing dune scrub.
Monterey gilia grows in sandy soils of dune scrub, coastal sage scrub, and maritime chaparral in the coastal dunes of Monterey County. This species is associated with dune scrub vegetation on sedimentary rocks and wind-blown deposits formed as the sea level rose since the end of the last ice age. The species occurs on recently stabilized U-dunes, semi-open older dune scrub of the Holocene age, and on Pleistocene dunes with coastal grassland and scrub vegetation.
This herb occurs in many topographic positions and aspects. Suitable habitat usually has a north, east, or west aspect or, in wet years, even a south aspect. The species occurs at elevations no higher than 100 ft (30.5 m). The substrate is sand with some soil development and litter accumulation. The species favors sites with limited exposure to strong winds, salt spray, and waves. It grows in open areas and wind-sheltered openings in the low-growing dune scrub vegetation and in areas where the sand has experienced some disturbance, such as along trails and roads. The species is usually tolerant of small amounts of drifting sand but tends to occur in stable sites with minimal sand accretion or deflation. Dynamic dune succession involving vegetative stabilization of mobile dunes and remobilization of dunes with dense dune scrub are likely to cause shifts in the distribution and abundance of Chorizanthe populations within dune systems in the long term.
Monterey gilia is endemic to the Monterey Bay and Peninsula dune complexes and is known from 15 extant occurrences with 110,400 individuals. It is distributed in discontinuous populations from Spanish Bay on the Monterey Peninsula, northward to Moss Landing. There are 15 known natural occurrences of this subspecies. One of the largest known occurrences of Monterey gilia was discovered at Fort Ord in 1993. Preliminary estimates indicated that as much as 60% of the total known individuals of this species may occur at Fort Ord.
Overall, this species is threatened by the degradation of suitable habitat by encroaching invasive plants, trampling by equestrians and pedestrians, and loss of habitat to development. Off-road vehicles have contributed to the degradation.
Conservation and Recovery
In addition to the protection prescribed for all endangered species by the various municipalities, efforts have been taken specifically for Monterey gilia.
Base closure of Fort Ord has resulted in the transfer of management of some habitat for this species to the U.S. Bureau of Land Management, University of California, and the California Department of Parks and Recreation to be managed as open space. Approximately 73% of the known habitat for Gilia on the former base will be protected. A Gilia restoration plan was prepared by the California Department of Parks and Recreation to increase the Fort Ord coastal occurrence by 14,000-18,000 individuals as part of an effort to restore 700 acres (280 hectares) of coastal dune habitat.
Numerous research studies are ongoing or have been completed for Monterey gilia, including the survival of seeds directly planted in dunes versus outplanting of greenhouse-raised seedlings. Studies concluded that greenhouse germination was almost 100%, compared with 6-15% of seed sown in dunes. The low field germination rates were attributed to variability in rain. Seeds have been collected for seed banking by the Rancho Santa Ana Botanic Garden. An experimental revegetation site at Spanish Bay golf course was not successful and no plants are present at that site.
U. S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
Eastside Federal Complex
911 N. E. 11th Ave.
Portland, Oregon 97232-4181
Telephone: (503) 231-6121
U.S. Fish and Wildlife Service. 22 June 1992. "Endangered and Threatened Wildlife and Plants; six Plants and Myrtle's Silverspot Butterfly From Coastal Dunes in Northern and Central California Determined to Be Endangered." Federal Register 57 (120): 27848-27858.