Stems submersed, to 1 m; lvs in whorls of 5-7, verticillately branched into filiform segments, many of which bear a terminal bladder; flowering branches 3-15 cm, 1-4- fld; cor 1 cm, violet or red-violet, the lower lip with a basal yellow spot, 3-lobed, the lateral lobes strongly and separately elevated at base into a palate; spur shorter than and appressed to the lower lip. Quiet water; Que. and N.S. to Minn. and n. Ind., s. along the coastal plain to Fla. and La.; W.I. July-Sept. (Vesiculina p.)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.