Mimulus alatus Aiton

Sharpwing Monkey Flower

© SRTurner

Family - Phrymaceae

Habit - Perennial forb with fibrous roots, often also with rhizomes or stolons.

Stems - Strongly ascending to erect, to 1.2 m, branching above or simple, 4-angled with the angles mostly narrowly winged, glabrous.

	Stem and node.
© SRTurner

Leaves - Opposite, simple, decussate, petiolate. Petioles 1-2 cm long, sometimes narrowly winged, not clasping the stem. Leaf blades 4-13 cm long (the uppermost often shorter and bractlike), 3-5 times as long as wide, broadly lanceolate to ovate or elliptic-ovate, angled or tapered at the base, tapered to a sharply pointed tip, the margins relatively sharply and finely to coarsely toothed, the surfaces glabrous, the venation pinnate.

	Stem and leaves.
© SRTurner

	Leaf adaxial.
© SRTurner

	Leaf abaxial.
© SRTurner

	Pressed leaves.
© DETenaglia

Inflorescences - Solitary axillary flowers, or on short axillary branches, the stalks 2-10 mm long, sometimes elongating to 3-17 mm at fruiting.

	Inflorescence.
© SRTurner

Flowers - Calyces 11-19 mm long, nearly actinomorphic, narrowly funnelform, the lobes 0.8-2.5 mm long, broadly ovate-triangular to semicircular, the thickened midrib of each sepal often extending past the body of the lobe as a short, stiff, straight awn, glabrous externally. Corollas bilabiate, 20-40 mm long, light blue to pale purple, finely glandular-hairy, the upper lip 2-lobed, usually strongly curved or bent outward, the lower lip 3-lobed, with a pale yellow area toward the base, this usually at least faintly red-spotted, the throat usually appearing more or less closed by the prominent, blunt ridges of the lower lip. Stamens 4, didynamous, adnate at base of corolla tube, included. Filaments white, glabrous, 6-7 mm long. Anthers brownish, 1.3 mm broad. Style included, white, glabrous, 7 mm long. Stigmas 2, flattened. Ovary 2-locular, light green, glabrous, 6 mm long, ovoid-conic. Placentation axile.

	Calyces.
© SRTurner

	Flower.
© DETenaglia

	Corolla.
© SRTurner

Fruits - Capsules 8-12 mm long, ovoid to narrowly ellipsoid-ovoid, glabrous. Seeds 0.3-0.4 mm long, oblong-ellipsoid to ellipsoid-ovoid, the surface with a fine network of ridges, light brown to brown.

	Developing fruits in persistent calyces.
© SRTurner

Flowering - June - September.

Habitat - Streambanks, pond margins, sloughs, oxbows, fens, seeps, swamps, bottomland forests, ditches, wet roadsides.

Origin - Native to the U.S.

Lookalikes - M. ringens.

Other info. - This species is found in moist areas throughout most of Missouri, less commonly in the northwestern quadrant of the state. It is common across most of the eastern half of the continental U.S.

Plants of this genus are easy to ID in the field because of their large, showy, irregular flowers. The two species are easily differentiated, as M. alatus has relatively short flower stalks and leaves with petioles. The primary lookalike, M. ringens, has sessile leaves and long stalks on the flowers. However, the two species are often found growing in close proximity, as they require the same moist habitat, and will often cross. The hybrid offspring exhibit a range of characters which can be intermediate or contradictory, and these plants can be hard to assign.

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 has been called fo. albiflorus House. The normal, lavender colored form is fo. alatus.

Photographs taken off 53rd Terrace, Platte County, MO., 8-17-00, and in the Ozark Scenic Riverways, Shannon County, MO., 8-12-03 (DETenaglia); also at Busch Wildlife Area, St. Charles County, MO, 7-29-2007, 7-31-2009, 7-27-2011, and 7-29-2015, along Fox Creek, St. Louis County, MO, 7-13-2012, and at Otter Slough Conservation Area, Stoddard County, MO, 8-15-2021 (SRTurner).