Wednesday, July 23, 2008
I'll take a stab at this game. This is a photo of Platanthera leucophaea, the eastern prairie fringed orchid, one of the rarest plants in the eastern United States, an unusual feat for a formerly widespread species. In Michigan, this species was historically common on lakeplain prairies along Saginaw Bay and farther south on Lake Erie, Lake St. Clair, and associated drainages. Eastern prairie fringed orchid was also formerly widespread, if local, in the interior counties of southern Lower Michigan, where it occurred in sphagnum bogs developed on carbonate-rich lakes and floating sedge peat mats. Alas, the lakeplain prairies fell to the plow in the early 1900s, and many of the inland populations of this species were destroyed by natural or anthropogenic disturbances, primarily shrub encroachment and hydrologic alteration. Today, eastern prairie fringed orchid hangs on in generally low numbers in ditches and habitat fragments that barely resemble original prairie. The above photo was taken at a site in Huron County, one of the very few intact lakeplain prairies contiguous with Lake Huron. This is important, because orchid populations move with lake levels, seeding lakeward in low water years and landward in high water years. The past 10-15 years have brought on rapid expansion of the non-native halotype of Phragmites australis (common reed) in areas that would have historically been colonized by prairie species during low water years. Landward, shrub encroachment limits the availability of bare, moist substrate the orchid requires. If this species is to survive in Michigan, considerable and persistent restoration and management effort will need to take place. Isn't she pretty?