Most botanical references place the genus Mimulus in the Snapdragon family, Scrophulariaceae; but modern genetic studies have persuaded botanists to remove it to the family Phrymaceae, the Lopseed family, which had previously had only one species in it.
Gray’s description of this species depends on his description of M. ringens, so we print that description in brackets:
MÍMULUS L. MONKEY FLOWER. Calyx prismatic, 5-angled, 5-toothed, the uppermost tooth largest. Upper lip of corolla erect or reflexed-spreading, 2-lobed; lower spreading, 3-lobed. Stigma 2-lobed; lobes ovate. Seeds numerous. — Herbs, with opposite (rarely whorled) leaves, and mostly handsome flowers. (Diminutive of mimus, a buffoon, from the grinning corolla.)
Corolla violet-purple (rarely white); erect glabrous perennials; leaves feather-veined.
[M. ríngens L. Stem square, 1 m. or less high; leaves oblong or lanceolate, pointed, clasping by a heart-shaped base, serrate; peduncles longer than the flower; calyx-teeth taper-pointed, nearly equal; corolla personate, 2-4 cm. long. — Wet places, N. B. to Man., and southw. June-Sept.]
M. alàtus Ait. Stem winged at the angles; leaves oblong-ovate, tapering into a petiole; peduncles shorter than the very short-toothed calyx; otherwise like the preceding. — Wet places, Ct. to s. Ont., Kan., and southw.