About Dodecahema leptoceras (A.Gray) Reveal & C.B.Hardham
Dodecahema is a genus of flowering plants in the buckwheat family (Polygonaceae), containing only one species: Dodecahema leptoceras, commonly known as slender-horned spineflower. This species is restricted to California, United States, where it is classified as endangered at both the state and federal levels. It is a small annual plant that grows as a low patch of spreading basal leaves; the patch is typically a few centimeters across, and may grow slightly larger when more moisture is available. The plant produces an erect stalk that holds inflorescences of flowers. Each cluster of white or pink flowers is enclosed in a small cup of fused bracts that is only a few millimeters wide. Its fruit is a dark achene that measures approximately 2 millimeters long. Slender-horned spineflower grows in silt-rich floodplains and washes in the foothills of the Transverse Ranges and Peninsular Ranges of southern California. Fewer than 40 confirmed sightings of the plant have been recorded, and many of these original locations have since been developed or otherwise altered. Currently, only about 19 distinct existing populations are believed to remain. This plant has only been documented in a small number of specific areas, including Tujunga Wash and the floodlands around the Santa Ana River and San Jacinto River. The main threats to this species include water diversion, activity from off-road vehicles, non-native invasive plant species, and development on private land, where most of the remaining populations are located.
