Mimulus ringens is a species of monkeyflower known by the common names Allegheny monkeyflower and square-stemmed monkeyflower. It is native to eastern and central North America. Naturalized in moist to wet soils in water or bog gardens, wet meadows.
Mimulus ringens, commonly called Allegheny monkey flower or square-stemmed monkey flower, is a rhizomatous, Missouri native, upright perennial which typically occurs in swampy areas, wet meadows, pond/streambanks and low woods throughout the State. Typically grows 1-3' (less frequently to 4') tall on erect, square, sometimes branching stems. Features lilac-purple, snapdragon-like flowers (to 1" long) with two-lipped, open-mouthed corollas. Flowers appear in pairs in the leaf axils on slender 1-2" long pedicels. Each flower purportedly resembles the face of a smiling monkey (hence the common name). Flowers bloom throughout the summer. Sessile, opposite leaves (2-4" long) are oblong to lanceolate and sharply-toothed. It can be invasive in North America.