Acmispon rigidus, synonyms Lotus rigidus and Ottleya rigida, is a flowering plant in the pea family (Fabaceae), native to the southwestern United States and northwestern Mexico.

The leaves are irregularly pinnate or palmate with three or five leaflets, 5–17 mm long.

The flowers are yellow to cream, turning red or purple as they age.

[5] Acmispon rigidus is found in the southwestern United States (Arizona, California, Nevada and Utah) and in northwestern Mexico.

[3] It is found on dry slopes and desert dry washes below 6,000 ft above sea level, in Joshua tree woodland, and in pinyon-juniper woodland plant communities.