AppearanceIndividuals of this species can range from 15 cm to 91 cm in height, depending on growth conditions. Its root system consists of taproot and thick rhizomes. The flowers are bisexual and bilaterally symmetrical, and most commonly blue to violet. It has erect, hollow, smooth, square stems that sometimes branch off. There are also thin wings along the angles of the stem.
The glabrous opposite leaves in a decussate arrangement are noticeably toothed and are up to 12 cm long and 5 cm wide. They are ovate, lanceolate-ovate, or lanceolate, gradually narrowing to a sharp point at the apex. At the base are narrowly winged petioles about 1.2 cm long.
NamingAt first glance ''Mimulus alatus'' is often confused with ''Mimulus ringens'', or the square-stemmed monkey-flower, because ''M. alatus'' occurs in several of the same habitats that ''M. ringens'' does. However, close examination of the two monkey-flowers can help differentiate them. ''M. ringens'' has sessile leaves and pedicels that are greater than 1.2 cm in length, whereas ''M. alatus'' have winged petioles and its pedicels are much shorter than 1.2 cm. The flowers of ''M. ringens'' are borne on pedicels longer than its calyx and for ''M. alatus'', it is the opposite – its pedicels are shorter than its calyx. The leaves of ''M. ringens'' are weakly toothed and stems unnoticeably winged. Also, it is noted that ''M. ringens'' can tolerate wider ranges of habitat conditions whereas ''M. alatus'' is more conservative.
Distribution''Mimulus alatus'' is a native species to eastern North America; its range stretches from Connecticut, down south to Florida and extends as far west as Nebraska and Texas. It is most commonly found in central and lower Mississippi valley, and considered rare in Connecticut, Iowa, Massachusetts, Nebraska, New Jersey, New York and Ontario.
HabitatThe sharp wing monkey-flower is a perennial that grows best under partial sun exposure and wet to moist conditions. It has been found in a variety of wetland types such as edges of small rivers, swamps, shady stream banks, wet woods, marshes, wet meadows, ditches, springs, etc. Full sun is tolerable but when it is grown in habitats that are too dry and sunny, the sharp wing monkey-flower remains small in size and becomes yellowish green. During its season it can endure occasional flooding and foliar disease is infrequent. It prefers a slightly acidic to neutral soil pH of 5.6-7.5 that contains plenty of organic matter. Temperatures below -23 °F are not survivable.
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