Publication: Ann. Missouri Bot. Gard. 9: 303. 1923.
selected vouchers: WS
Notes: FNA7: "Caulanthus lasiophyllus is highly variable in flower size, leaf morphology, fruit morphology (length, width, curvature, presence or absence of indumentum) and orientation, number of ovules per ovary, and plant height. This species is badly in need of thorough studies at both populational and molecular levels, and it is very likely that some varieties recognized by E. B. Payson (1923), such as var. rigidus, may well represent distinct species or subspecies."
Last collections made in Washington in the 1940s, are held at PSM, and need verification.