Stems 2-8 dm; herbage glabrous; lvs dark green, linear- oblong to narrowly lanceolate, 4-9 cm, seldom 1 cm wide, narrowed to the base; fls mostly few in a terminal cluster, often also some in the upper axils; involucral lvs spreading; cal-lobes linear or narrowly oblong, 4-12 mm; cor blue to sometimes white, 3-5 cm, narrowly open, the incurved lobes broadly ovate, obtuse or rounded, exceeding the obliquely triangular, entire or 1-toothed plaits by 3-5 mm; anthers connate; 2n=26. Wet woods and meadows; Que. and sw. Lab. to N.B., N.J., Pa., and s. Ont., s. locally to Tenn., and w. on granitic or otherwise acid substrates to the Lake Superior region of Mich. and Ont. Aug., Sept.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.