Mimulus alatus Ait. - Monkey Flower

Mimulus alatus plant

Family - Scrophulariaceae

Stems - To +/-70cm tall, erect, branching above or simple, 4-angled, glabrous, hollow, from thick rhizomes, herbaceous. Angles winged.

Leaves - Opposite, decussate, petiolate. Petiole to 1cm long, with a small wing adaxially. Blade to -10cm long, +3cm broad, lanceolate to lance-ovate, acuminate, shallow serrate to crenate-serrate, glabrous.

Mimulus alatus leaves

Inflorescence - Single flowers from leaf axils. Pedicles 5mm in flower, slightly longer in fruit.

Flowers - Corolla bilabiate, purple. Corolla tube to 1.5cm long, glandular pubescent near apex, glabrous below. Upper lip erect to reflexed, 2-lobed. Lobes glandular pubescent externally. Lower lip 3-lobed. Lobes spreading, glandular pubescent internally and externally., subequal, rounded to obtuse. Central lobe yellow-bearded at base(apex of throat). Stamens 4, didynamous, adnate at base of corolla tube, included. Filaments white glabrous, 6-7mm long. Anthers brownish, 1.3mm broad. Style included, white, glabrous, 7mm long. Stigmas 2, flattened. Ovary 2-locular, light green, glabrous, 6mm long, ovoid-conic. Placentation axile. Calyx tube to 1.7cm long, 5-ribbed, glabrous, 5-lobed. Lobes 2mm long, mucronate. Capsule to +1cm long, many seeded, glabrous.

Mimulus alatus calyxCalyx.

Mimulus alatus corollaCorolla.

Flowering - June - September.

Habitat - Stream borders, low wet woods, wet meadows, ditches, springs.

Origin - Native to U.S.

Other info. - Plants of this genus are easy to ID in the field because of their large, showy, irregular flowers. The yellow beard on the corolla serves as a guide to bring insects to the flower and the lobes of the flower serve as landing platforms.
A white flowered form of this species, form albiflorus House, has been found in a few counties in the state. The typical flower color is shown above, and these plants are form alatus.

Photographs taken off 53rd Terrace, Platte County, MO., 8-17-00, and in the Ozark Scenic Riverways, Shannon County, MO., 8-12-03.


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