The genus name Mimulus is a Latin term (mimus) meaning buffoon or actor in a face or mime. The common name 'monkey flower' refers to the resemblance of the flowers to small, grinning, ape-like faces. Many of the members of this genus are suitable for growth in woodland gardens which are seasonally moist. The plants have opposite leaves, stalked or non-stalked, with smooth or shallowly toothed edges. Flowers grow on stalks from the leaf axils or in terminal clusters, which are often rather large and showy. The sepals are joined to a calyx which is tubular, regular to irregular, the lobes are shorter than the tube. The petals are joined to a corolla which form 2 spreading lips, an upper and a lower lip. The upper lip has 2 lobes and the lower lip has 3 lobes. Some species have larger lower lip than upper, but some have 5 lobes of almost equal size. The flowers are colored yellow or pink-violet and have 4 stamens, in 2 pairs of differing lengths, and 2 distinct stigmas. The seed capsule is cylindric. Monkey-flowers are unusual in having a peculiar two-lobed stigma that is irritable when touched. A bee entering a flower brushes first against the stigma, whose two lobes fold together quickly and lie tightly pressed against the upper surface of the corolla tube. In so doing, the stigma with its pollen load is positioned in a way that makes the bee come into contact with the flower's anthers which lie behind the lower stigmatic lobe. This active movement mechanism insures pollen reception by the stigma and pollen deposition on the insect for subsequent flower visits.
Guide to Identify Presented Species of Genus Mimulus
FLOWERS YELLOW, AT LEAST 15 MM LONG
M. guttatus Yellow Monkeyflower Stems erect or trailing, branched, 10-50 cm tall. Wet sites, foothills to subalpine.
Flowers large, yellow, red-spotted, several in loose clusters. Lower lip large.
Leaves egg-shaped. Lower leaves larger, often with ragged lobes at bases.
FLOWERS PINK OR PURPLE
M. lewisii Purple Monkeyflower Stems sticky-hairy, 30-70 cm tall. Moist, open sites, montane to alpine.
Flowers large, pink-purple with yellowish throats, in clusters, long-stalked.
Leaves lance- to egg-shaped with strong parallel nerves, stalkless, toothed.