Mimulus glabratus var. michiganensis
|Dawn M. Gerlica|
The following Participating Institutions are custodians for this species in the CPC National Collection:
The Holden Arboretum
The conservation of Mimulus glabratus var. michiganensis is fully sponsored.
Dawn M. Gerlica contributed to this Plant Profile.
This plant is a mat-forming, semi-aquatic perennial. The stems can reach 40 cm or more in length and usually trail along the ground, rooting at the leaf nodes, and forming dense mats. The evenly distributed, coarsely toothed leaves are opposite each other along the stems. The bright yellow snapdragon-like flowers can be 16-27mm long. The upper lip is 2 lobed and the lower is 3 lobed with irregular red spots. Look for blooms between mid June to mid July produced from the axils of the upper leaves.
Even though this species has very specific needs, it has proven its ability to survive against all odds. Results of studies with an infrared gas analyzer have clearly shown that the plants can survive in drier conditions, but recorded twice the photosynthesis and transpiration if they were partially submersed.
Most sites are on private property which adds a challenge to protection. Education programs have been started to preserve the remaining populations. One population has dared to persist, despite repeated mowing, in a localized colony where spring water comes to the surface in a homeowner's lawn.
Studies have shown that very little of the pollen is actually viable and likewise very little viable seed is produced. The dense mats formed by the stems allow for propagation from clones that are created when portions of the stem break off and take root wherever the stream drops them.
Distribution & Occurrence
This species is usually found in sunny areas, rooted in silty, sandy, alkaline mud, and growing out of a stream of cool running water. The preferable summer water temperature usually ranges between 8.7 to 16.6 degrees Celsius. The pH is usually found to be between 7.66 to 8.21.
|Within reports over the past 10 years, the number of existing sites for populations of this species varies greatly. In the most recent abstract, it is known to occur in only 17 locations within the Grand Traverse and Straits of Mackinac regions in the state of Michigan. Two of these sites are historical and populations have not been found on recent searches, although persistent colonies have been found in other areas along the same lakes. Larger populations are known to occur on Glen Lake, Burt Lake, and part of the Mackinac county shoreline. Actual numbers of plants are difficult to determine because of the nature of the mat-forming habit. (Penskar 2001)|
Conservation, Ecology & Research
Potential low genetic diversity
Local hydrology changes from human or natural occurrences, including: fluctuating lake levels, raised water temperatures, and diversions by roads or construction (Ostlie 1990)
Population monitoring and demography are needed to guide future management decisions. (Penskar 2001)