M. palustris: stems weak, ascending, 1/2-1 1/2 foot high, nearly glabrous; leaves oblong bluntish, nearly glabrous; flowers bright clear blue, with a yellow eye, rather large; calyx never divided below the middle. - Forget-me-not. - Wet ditches and sides of streams. Fl. June to August.
M. repens, which is more hairy, with narrower lobes to the calyx, reaching to about the middle; and M. csespitosa, which has a smaller corolla, with the limb often slightly concave, are varieties sometimes considered distinct.
M. sylvatica: stems one foot high, roughly hairy; leaves oblong-lanceolate; flowers large, handsome, blue, the limb spreading flat; calyx cleft nearly to the base, with narrow segments. - Mountain pastures and shady situations. Fl. Mav, June.
The alpine form, with larger flowers, is by some distinguished as a species, under the name of M. alpestris.
M. arvensis: annual or biennial; stem weak, a foot high; leaves oblong, acute, hairy; flowers small, blue; the corolla with a short, concave limb; calyx deeply cleft, the narrow segments erect when in fruit. - Cultivated ground and bushy places. Fl. June to August.
†† Peduncles shorter than the calyx.
M. collina: annual; stems much branched, hairy, seldom six inches high; leaves in radical tufts, oblong obtuse; flowers in slender racemes, the corolla very small, bright blue, with a small, concave limb. - Dry, open places. Fl. May.
M. versicolor is a little hairy annual, something like the last, but with a more simple and erect stem, a spreading tuft of radical leaves, and small nearly sessile flowers; the corolla at first pale yellow, turning blue as it fades.