M. víridis, L. (Spearmint.) Nearly smooth; leaves oblong- or ovate-lanceolate, unequally serrate; bracts linear-lanceolate and subulate, conspicuous.—Wet places; in all cultivated districts.
[*][*] Flowers pedicellate, less crowded, in interrupted leafless spikes, or some in the upper axils; leaves petioled.
M. piperìta, L. (Peppermint.) Glabrous (somewhat hairy in var. SUBHIRSÙTA), very pungent-tasted; leaves ovate-oblong to oblong-lanceolate, acute, sharply serrate; spikes narrow, loose.—Along brooks, escaped everywhere.
M. aquática, L. (Water Mint.) Pubescent or smoothish; leaves ovate or round-ovate; flowers in a terminal globular or interrupted and oblong head, often with one or more clusters in the axils of the upper leaves; calyx and usually the pedicels hairy. The common form has the stems hairy downward.—Wet places, N. Eng. to Del.; rare.—Var. críspa, Benth., is a glabrous or glabrate form, with lacerate-dentate and crisped leaves.—Ditches, N. J., etc.
[*][*][*] Flowers in globular whorls or clusters, all in the axils of the leaves, the uppermost axils not flower-bearing; leaves more, or less petioled, toothed.
M. satìva, L. (Whorled Mint.) Stem hairy downward; leaves ovate, sharply serrate; calyx oblong-cylindrical with very slender teeth.—Waste damp places, Mass. to Penn.; not common. Passes into the next.
M. arvénsis, L. (Corn Mint.) Lower and smaller-leaved than the last; leaves obtusely serrate; calyx bell-shaped, the teeth short and broader.—Moist fields, N. Eng., etc.; rare.
1. M. Canadénsis, L. (Wild Mint.) Leaves varying from ovate-oblong to lanceolate, tapering to both ends; calyx oblong-bell-shaped, the teeth rather short; hairs on the stem not conspicuously reflexed. The commoner form is more or less hairy, and has nearly the odor of Pennyroyal.—Wet places, through the northern U. States across the continent, and northward.
Var. glabràta, Benth. Leaves and stems almost glabrous, the former sometimes very short-petioled; scent sweeter, as of Monarda.—Similar range.
8. LÝCOPUS, Tourn. Water Horehound.