Erect, 5-8 dm, simple or branched above; lvs linear to lance-ovate, to 15 cm, acuminate, serrate with salient or ascending teeth, on a short indistinct petiole, or tapering to a sessile base; spikes 3-8 cm, subtended by scarcely reduced foliage-lvs; cor 2.5-3.5 cm, white, or partly greenish-yellow, or tinged with pink, or even purple toward the summit, the palate white-bearded; staminode green; 2n=28. Wet woods; Nf. to Minn., s. to Ga. and Ala. July-Sept. Highly variable, with ±evident regional trends of variation.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.