Annual to 7 dm, widely branched from the base, the upper parts and petioles viscid-villosulous, the hairs ca 0.5 mm; lvs ovate, 3-6 cm, shallowly and unevenly repand-dentate, broadly acute to rounded at base, often inequilateral; pedicels at anthesis 3-5 mm, to 1 cm at maturity; fls 7-10 mm, yellow; cal-lobes deltoid, about as wide as long; anthers 0.7-1.2 mm; fruiting cal obscurely angled, 2-3 cm. Dry upland woods and barrens; Mo. to se. Neb., Kans., Okla., and Ark. May-Sept. (P. pubescens var. m.)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.