Stems 1-12 dm, simple to much branched, quadrangular, smooth to the touch; largest lvs to 4 mm wide; axillary fascicles of lvs wanting or only weakly developed, except in var. "racemulosa"; fls few-many, on pedicels 1-4 mm; cal-tube 2-4 mm, the lobes triangular, usually acuminate, 1 mm or more, the sinuses generally broadly rounded; cor purple (white), its upper lobes reflexed-spreading, pubescent within; fr subglobose, 4-6 mm; seeds dark; 2n=28. Moist, especially sandy soil of bogs, shores, and barrens, usually in sun; N.S. to Minn. and S.D., s. to Fla., Mex., and W.I. (Gerardia p.) Three or four poorly marked vars.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.