Ruellia humilis Nutt.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Species Description - Stems 2–6 dm; lvs sessile or subsessile, 3–8 cm, acute to very obtuse; fls in sessile or subsessile, crowded cymose clusters from the axils of several upper lvs, subtended by lanceolate bracts; cal-lobes narrowly linear to subsetaceous, less than 1 mm wide; cor 3–7 cm; fr glabrous. Prairies and dry upland woods; Pa. to n. Ind., se. Minn., and Nebr., s. to w. N.C., Ala., and Tex. (R. ciliosa, misapplied) Highly variable in lf-form, pubescence, and fl-size. The common and widespread var. humilis is copiously hairy on the young internodes, the pubescence commonly extending also to the cal-lobes and the veins and margins of the lvs. Var. calvescens Fernald, of the Appalachian region from s. O. and s. Ind. to Ky., Tenn., Ga., and Ala., is glabrous or only sparsely hairy.