A number of studies on slender-horned spineflower have been conducted with funding provided by U.S. Fish and Wildlife Service Section 6 money: An assessment of seed bank buffering of genetic change in slender-horned spineflower at 4 locations was conducted by Ferguson and Ellstrand, University of California Riverside (1999). Mycorrhizal associations within slender-horned spineflower habitat were studied in 8 locations. Typically, annuals within the buckwheat family do not form mycorrhizae. However, slender-horned spineflower was found to form associations, although not likely mutualistic, with arbuscular-mycorrhizal fungi. These associations were determined not to be a limiting factor in suitable but unoccupied habitat (Young et al. 2000) Various analyses have been conducted to characterize the habitat of slender-horned spineflower, from an ecological and geomorphic analysis. An attempt was made to characterize soils, vegetation cover, associated species, and ages of alluvial sediments that support populations of slender-horned spineflower (Allen 1996; Wood and Wells 1996). In addition, an investigation was made into the population biology of the slender-horned spineflower at 4 sites to determine population demographics, breeding systems, and genetic variation (Ferguson et al. 1996).

Previous efforts at growing slender-horned spineflower from germinated seeds have failed. More research is needed in establishing successful germination protocols and growing conditions for slender-horned spineflower if future management plans are to include the establishment of new sites (Ferguson et al. 1996).

There are thirty five occurrences known with only 19 still extant. The habitat where this species occurs, alluvial terrace, is highly threatened by development, agriculture, off-road vehicle use, non native plants and other threats. The long term trend for this species is one of significant decline due to the alteration and degradation of its habitat, alluvial terrace. Further, short term decline is also quite steep.

Many historical occurrences of this species have been lost to urbanization and stream channelization. Current threats include development, sand and gravel mining, flood control, hydrological alteration, proposed reservoir construction, off-road vehicle

There have been 37 reported occurrences of slender-horned spineflower in southern California, 23 are existing occurrences and 14 have been or are presumed extirpated. These occurrences are located in 8 general areas: Bee Canyon, Big Tujunga Wash, Lytle Creek/Cajon Canyon, Santa Ana River wash, Bautista Creek, San Jacinto River, Temescal Canyon, and Vail Lake/Dripping Springs area (CNDDB 2000).

A number of studies on slender-horned spineflower have been conducted with funding provided by U.S. Fish and Wildlife Service Section 6 money: An assessment of seed bank buffering of genetic change in slender-horned spineflower at 4 locations was conducted by Ferguson and Ellstrand, University of California Riverside (1999). Mycorrhizal associations within slender-horned spineflower habitat were studied in 8 locations. Typically, annuals within the buckwheat family do not form mycorrhizae. However, slender-horned spineflower was found to form associations, although not likely mutualistic, with arbuscular-mycorrhizal fungi. These associations were determined not to be a limiting factor in suitable but unoccupied habitat (Young et al. 2000) Various analyses have been conducted to characterize the habitat of slender-horned spineflower, from an ecological and geomorphic analysis. An attempt was made to characterize soils, vegetation cover, associated species, and ages of alluvial sediments that support populations of slender-horned spineflower (Allen 1996; Wood and Wells 1996). In addition, an investigation was made into the population biology of the slender-horned spineflower at 4 sites to determine population demographics, breeding systems, and genetic variation (Ferguson et al. 1996).

Most of the known occurrences of slender-horned spineflower are located on private property threatened by development, only several occurrences are located on federal lands (national forest system lands) and managed as sensitive.

Management recommendations for slender-horned spineflower have prescribed the preservation of older, stable alluvial and/or stream surfaces in washes for protection of this plant species (Wood and Wells 1996) and for the potential establishment of new populations.

Previous efforts at growing slender-horned spineflower from germinated seeds have failed. More research is needed in establishing successful germination protocols and growing conditions for slender-horned spineflower if future management plans are to include the establishment of new sites (Ferguson et al. 1996).