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Literature in Review

Little San Bernardino Mountains Gilia

Gilia maculata

USFWS: Species of Concern, Candidate for listing
CDFG: No official status

Background

Distribution, Abundance and Trends. The Little San Bernardino Mountains gilia is a tiny endemic plant species which is found in a restricted range in the vicinity of the Little San Bernardino Mountains near Desert Hot Springs, in Mission Creek canyon across Hwy. 62 to Dry Morongo Wash and Big Morongo Canyon and near the mouth of Dry Morongo Canyon in the northwestern portion of the Coachella Valley, in Whitewater Canyon in the eastern San Bernardino Mountains, and from Whitewater to Palm Springs, the type locality. There is one very recently described location in Rattlesnake Canyon on the north side of the San Bernardino Mountains. The most extensive populations of this species are outside the Plan boundary, along washes at the northern edge of Joshua Tree National Park, in the vicinity of Joshua Tree, Yucca Valley and Twentynine Palms. It seems likely that additional populations of this species may occur in the area of approximately 22 miles between Rattlesnake Canyon and Yucca Valley.

The size and ephemeral habit of the Little San Bernardino Mountains gilia have made it difficult to find and hence it is little collected and studied. This tiny desert annual was first described by Parish in 1892 from a collection at "Agua Caliente" (= Palm Springs) in 1889; the location of this collection was described as just west of the hot springs in Palm Springs. The next collection was at Joshua Tree in 1924. It was little known until Patterson (1989) described more exactly its preferred habitat. More records have been reported in the last five to ten years.

The preferred habitat of Little San Bernardino Mountains gilia is in loose soft sandy soils on low benches along washes, generally where the substrate shows some evidence of water flow. It seems to occur in areas where few or no competing species are found, with little shrub or tree cover in the immediate vicinity. The sand is loose and well-aerated, soft and unconsolidated (Sanders 1999). The known locations within the Plan area are on the margins of washes on shallow sandy benches, not on areas where a hard surface layer occurs, and not on loose blowsand away from washes. This gilia has a slender tap root that can extend over 6 cm into the sand, presumably allowing it to avoid atmospheric drying. It is associated with creosote bush scrub, but avoids growing in the shadow of other plants. The elevational range of the species is from 500 to 4000 feet.

Little is known of the life history of this species. Its pollinators, germination requirements, seed longevity, and population parameters have not been described. The flower form and color are indicative of insect pollination but no information on pollination ecology is available. The plants are very small, generally reaching a height of only 0.8 to 1.2 inches. They have a slender, little-branched tap root that may extend over 3 inches into the sand, probably allowing the plants to tap subsurface supplies of moisture and thus avoid atmospheric drying. They are nevertheless very ephemeral.

No comprehensive population estimates have been made, but records for the species give an idea of the size of the known populations. In Dry Morongo Canyon Helmkamp (in Sanders 1999) reported a few hundred plants in 1995 but only six in 1996. At the mouth of Big Morongo Canyon north of Indian Avenue more than 10,000 plants were in spring of 1996. Populations in the Whitewater River area have been reported in the range of 200 individuals. In Mission Creek wash east of old Highway 62, Helmkamp reported a single population of more than 2,000 plants in 1992. Clearly, populations vary with environmental conditions in a given year.

Threats and Limiting Factors. The greatest threat to this species is growing urbanization in the vicinity of Desert Hot Springs and Highway 62 where the largest populations exist. Only 6% of the known locations for Little San Bernardino Mountains gilia are currently protected in existing public or private conservation areas. Urbanization spreading westward from Desert Hot Springs could eliminate the most significant populations in the long term. Development pressures are a concern primarily in the Mission Creek drainage east of Hwy. 62 and in the vicinity of Dry Morongo Wash near Hwy. 62 and Indian Avenue. One disturbance that may impact this species is flood control maintenance activities in the Whitewater Canyon and Mission Creek drainages. Another threat to this species is OHV activity in the wash habitat where it occurs. The small size of the plants and their occurrence along the margins of washes, which may serve as routes of travel for OHV users, make them particularly vulnerable to vehicle damage.

Special Considerations. Within the Plan area, all populations not on public land must be considered highly threatened as they occur on relatively flat sits and predominantly on private land.