Slender annual 1-5 dm, obscurely strigose to evidently hirsute-puberulent; lvs mostly 1-4 cm נ2-8 mm; "racemes" naked or with one or two leafy bracts near the base, not much if at all longer than the leafy part of the plant; fruiting pedicels 1-3 mm, evidently shorter than the 3-5 mm cal, ascending or somewhat spreading; cal-tube shortly uncinate-hispid; cor at first yellow or yellowish, ordinarily changing to blue, the limb 1-2 mm wide, not flat; nutlets shorter to occasionally longer than the style; 2n=64. Native of Europe, locally intr. in fields and roadsides; Que. to Va. May-July. (M. versicolor)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.