Michigan Monkey-flower

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Michigan Monkey-flower

Mimulus glabratus var. michiganensis

ListedJune 21, 1990
FamilyScrophulariaceae (Snapdragon)
DescriptionSemi-aquatic perennial with yellow, two-lipped, tubular flowers.
HabitatCold, saturated soils along seepages, streams, and lakeshores.
ThreatsRecreational and residential development.


Michigan monkey-flower is an aquatic or semi-aquatic perennial in the snapdragon family. The smooth, prostrate stems average 14 in (36 cm) in length. The leaves are round, opposite, coarsely toothed, and evenly distributed along the stem. From mid-June to mid-July (sometimes into August) yellow flowers, ranging from 0.6-1.1 in (1.6-2.7 cm) in length, bloom on stalks that emerge from the upper leaf axils. The tubular flowers have a two-lobed upper lip and a three-lobed lower lip; the lower lip and tube are spotted with red. Reproduction is primarily vegetative; the lower stem nodes root and produce clumps of up to several hundred individual stems.

Close relatives of Michigan monkey-flower areM. glabratus var. fremontii and M. guttatus. While these species are extremely similar in appearance, they can be distinguished through the measurements of floral parts. Those of var. michiganensis are larger than those of var. fremontii but generally smaller than those of M. guttatus. M. guttatus and var. michiganensis can also be differentiated by the shape of some of the flower parts.


The species grows in mucky soil and sand that is saturated or covered by cold, flowing spring water. Nearly all known populations occur near the present or past shorelines of the Great Lakes. Northern white-cedar (Thuja occidentalis) is usually the dominant tree; common associates include touch-me-not (Impatiens biflora), forget-me-not (Myosotis scorpioides), water-cress (Nasturtium officinale), spearmint (Mentha arvensis), and liverwort (Conocephalum conicum).


Michigan monkey-flower has been found at sixteen sites in the Mackinac Straits and Grand Traverse regions of Michigan. It was first collected in Harbor Springs (Emmet County) in 1890, but was not described until 1980. The type specimen (from which the first published description was made) was collected in 1925 along Niger Creek, near Topinabee (Cheboygan County). Other populations were discovered in Benzie, Leelanau, Charlevoix, and Mackinac Counties.

The species survives at twelve sites, two of which contain only one or two plants. Two-thirds of the plants occur on private land. Sites with some degree of protection include Sleeping Bear Dunes National Lakeshore and the University of Michigan Biological Station, which contain the three most abundant populations. The species also occurs in a township park and on land owned by the Michigan Nature Association, a private conservation group. The Maple River site in Emmet County contains the most significant population on private land. Plants at that site are the only ones that are producing viable pollen and setting seed. Along with another private site, it is registered with the Michigan chapter of The Nature Conservancy, affording it some informal protection. While population estimates of species that reproduce clonally are difficult to make, only four of the 12 existing sites support more than ten clumps of Michigan monkey-flower.


The principal threat to Michigan monkey-flower is the loss of its specialized habitat through recreational and residential development. Increased construction of vacation homes along lake and stream shores is known to have been responsible for the destruction of three populations; two others have been severely affected.

Besides direct disturbance, Michigan monkey-flower is vulnerable to any disturbance to its water supply. Road construction or other activities that alter water drainage patterns may affect populations.

Although there does not appear to be an organized commercial trade in Michigan monkey-flower, some collecting has occurred. In fact, one population was discovered when a botanist was served a sprig of Michigan monkey-flower as a garnish on a restaurant dinner plate.

Conservation and Recovery

The Fish and Wildlife Service published a Recovery Plan for the Michigan monkey-flower in 1997. This endangered plant only survives in 15 places, of which only 12 are considered to provide viable critical habitats. Two of the best habitats are on publicly owned land and are being conserved as natural areas. Its other critical habitats are on private land and are potentially threatened. The largest of these habitats should be protected by acquiring the land and designating ecological reserves, or by negotiating conservation easements with the owners. The populations of the Michigan monkey-flower should be monitored, and research undertaken into its biology, habitat needs, and beneficial management practices. A program of public education should be developed to alert local people of the importance of protecting this and other rare plants and their habitat.


U.S. Fish and Wildlife Service
Division of Endangered Species
Federal Building
1 Federal Drive
Fort Snelling, Minnesota 55111-4056
Telephone: (612) 713-5360
Fax: (612) 713-5292


Penskar, M. R. 1991. "Michigan Monkey-Flower(Mimulus glabratus var. michiganensis) Recovery Plan." U.S. Fish and Wildlife Service, Twin Cities, Minnesota.

U.S Fish and Wildlife Service. 1997. Recovery Plan for Michigan Monkey-flower (Mimulus glabratus var. michiganensis ). Fort Snelling, Minnesota.

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Michigan Monkey-flower