Acmispon watsonii aka Acmispon Watsonii

Acmispon watsonii (Vasey & Rose) Brouillet is a member of the legume family (Fabaceae), placed in the genus Acmispon — a North-American and west-South-American group of small herbaceous legumes commonly called bird's-foot trefoils and deervetches. The species was first described as Hosackia watsonii by Vasey and Rose; it has since circulated under the names Lotus watsonii (Vasey & Rose) Greene and Syrmatium watsonii (Vasey & Rose) Brand, and was transferred to Acmispon by Brouillet in Phytoneuron 2020-29 (2020). World Flora Online and Plants of the World Online treat all of these earlier names as synonyms of A. watsonii. Across GBIF, the species is also linked to the synonyms Hosackia alamosana Rose and Lotus alamosanus (Rose) Gentry, and the only common name attached at species level in those data sets is "Sonoran bird's-foot trefoil".

The native range of Acmispon watsonii is Mexico, principally Baja California, where Plants of the World Online records the species as growing primarily in the desert or dry shrubland biome. Distribution data flagged on POWO and GBIF extend across northwestern Mexico (the TDWG region "Mexico Northwest"), with documented records in the Mexican states of Baja California, Baja California Sur, Sonora, Sinaloa, Chihuahua and Durango. GBIF occurrence statistics weight the species heavily toward Mexico (710 records) compared with the United States (43 records); within the US it is documented chiefly in Arizona and, to a much smaller extent, in California. Specimen images on SEINet are drawn from BajaFlora.org and the San Diego Plant Atlas, reinforcing the picture of a Sonoran-Desert / Baja-California species that just reaches the south-western United States.

Beyond taxonomy and distribution, very little authoritative information is currently published online about Acmispon watsonii. Plants of the World Online lists its lifeform as "Unknown", and major horticultural and ethnobotanical references (RHS, Missouri Botanical Garden Plant Finder, Plants For A Future, Dr. Duke's Phytochemical Database) do not have entries for the species. Wikipedia lists the binomial within the Acmispon genus account but does not maintain a dedicated species article. The IUCN Red List has not evaluated Acmispon watsonii, and no invasive-species or noxious-weed listing was found in the sources consulted. As a result, characteristics that are well-documented for many congeners — life cycle, mature size, bloom period, soil and moisture preferences, hardiness, edibility and medicinal use — are not asserted for this particular species in the reputable sources reviewed.