Phacelia A.L. de Jussieu.
A genus of about 100-200 species, of North America and South America, concentrated in w. North America.
ID notes: 1. Phacelia bipinnatifida and Hydrophyllum virginianum are sometimes confused. P. bipinnatifida has the larger and more basal leaves distinctly bipinnatifid, the lower pinnae often stalked (vs. pinnatifid, the basal or terminal pinnae sometimes 2-lobed, all the pinnae more-or-less sessile), pubescence of the upper stem and inflorescence in part glandular (pubescence nonglandular), and seeds 4 per capsule, black (vs. 2 per capsule, light brown). 2. Phacelia covillei and P. ranunculacea are superficially similar to and sometimes confused with Nemophila aphylla, which see for discussion.
Ref: Constance (1949); Gillett (1964); Gillett (1968); Hofmann et al. In Kadereit & Bittrich (2016); Levy (1991a); Levy (2021); Levy & Malone (2001); Levy, Hou, & Taylor-Bennetts (2021); Murdy (1966); Sewell & Vincent (2006). Show full citations.