Much like no. 3 [Phacelia purshii Buckley], but the denticulate to fimbriate cor-lobes pilose on the back, the ovules mostly 8, and the 6-8 seeds 1.5-2 mm; 2n=18. Deciduous woods and limestone-barrens; c. Mo. to adj. Kans. and Okla. Apr., May.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.