This species is infrequent to frequent in the northwestern part of the state, where its habitat is frequent, and local or absent in other parts of the state where its habitat is absent. Its preferred habitats are moist, sandy soil on interdunal flats, in marshes, and springy places, wet prairies, and, in the southern part of the state, in hard, white clay soil in wet, open sweet gum woods and fallow fields.
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.