Rhizomatous perennial, glabrous throughout, with erect or ascending simple stems 1-10 dm; lvs opposite, all short-petiolate, serrate to subentire, lanceolate or lance-ovate to narrowly subtriangular, or the lower more elliptic, 1.5-8 נ0.6-3 cm, generally 2-4 times as long as wide; racemes axillary, pedunculate, open, mostly 10-15-fld; cor 5-10 mm wide, blue; style 2.5-3.5 mm; mature pedicels divaricate, 5-15 mm; fr turgid, 3 mm long and about as wide, scarcely notched; seeds numerous, 0.5 mm or less; 2n=36. Swamps and streambanks; Nf. to Alas., s. to N.C., Mo. and Calif.; also ne. Asia. May-Aug.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.