Asymmetrical, 2-lipped, blue-purple flowers rise from the axils of opposite leaves that clasp the square stem.
The flower looks something like a monkeys face, hence the common and genus names, the latter from the Latin mimus (a buffoon). A variety of this plant, M. ringens var. colpophilus, found from Quebec to Maine on tidal muds, is classified as an endangered species in Maine. The lavender-flowering Sharp-winged Monkeyflower (M. alatus) has stalked leaves and a winged stem. It is more common southward and westward in wet sites.