Perennial to 6 dm; stems glabrous, except commonly for a minute pubescent area at each node; fls 2-8 at each node in the upper half of the plant, subtended by progressively reduced lvs and each fl by 2 linear bracts; pedicels 3-10 mm; cal glabrous, 4-6 mm, the lips half as long as the tube, the lobes acuminate; cor pale purple, 8-15 mm; style-branches short, slender, unequal. Calcareous soil; May-Aug. Two vars.:

Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.

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