The western prairie fringed orchid or Great Plains white fringed orchid concludes the orchids of Manitoba series. Photographed at the Tolstoi Tall-Grass Prairie Preserve less than two weeks ago, this was one of only two plants we saw in flower. In a typical year in early July, I was told there should be hundreds in bloom, if not thousands. We spoke with someone in the area who had managed the land parcels for a couple decades: “It’s the worst year I’ve ever seen [for blooms]”. This, of course, was after walking a trail with ticks on a hot and muggy morning to find no discernible plants. Slow drives along the roadsides where the retired land parcel manager suggested they are typically easily found yielded no results. Finally, about 400m before the return to the highway and the trip back home, I spotted one.
While preparing to photograph it, Christie Borkowsky, a biologist with Manitoba’s Critical Wildlife Habitat Program, happened to drive by. I had met Christie several weeks earlier while unsuccessfully looking for Cypripedium candidum in bloom (plants were found). On this day, she was working on plant counts for this species. Her count? About ten. She confirmed that the count would normally be in the hundreds, if not more. Christie has been working with Platanthera praeclara for at least a decade, initially studying pollinators of the western prairie fringed orchid. For a more in-depth look at her research, see Westwood, AR and CL Borkowsky. 2004. Sphinx Moth Pollinators for the Endangered Western Prairie Fringed Orchid Platanthera praeclara in Manitoba, Canada. (PDF) Journal of the Lepidopterists’ Society. 58(1):13-20. As Christie was driving away, she pointed out the second plant in flower we saw that day about 40m down the road.
Platanthera praeclara is known only from the Great Plains of the USA and Manitoba (despite the broad range shown on the distribution map, it seems it has been declared extirpated in both South Dakota and Oklahoma). It is considered endangered in both the Canada and the USA, and is ranked A2ac by the IUCN Red List (Platanthera praeclara, meaning “An observed, estimated, inferred or suspected population size reduction of ≥ 50% over the last 10 years or three generations, whichever is the longer, where the reduction or its causes may not have ceased OR may not be understood OR may not be reversible, based on direct observation and a decline in area of occupancy, extent of occurrence and/or quality of habitat”. The section on populations of Platanthera praeclara on the IUCN site discusses both year-to-year fluctuations and overall declining trends in the species. For example, in Manitoba: “The number of plants occurring in Manitoba is difficult to determine because of dramatic fluctuations in numbers from season to season. A low of 1,818 plants were counted in 1995 and a high of 23,530 were recorded in 2003. Fluctuations in the number of flowering individuals are very common for this species, however, it is the overall decline in the numbers of reproductive individuals at each fragmented location which is of biological concern”. I suspect 2012 will show a new low for Manitoba. Though we speculated as to why (perhaps the late frosts in the area (the ones that damaged the blooms of Cypripedium candidum or the heat in early spring followed by cool weather), it would require study since there are so many potential variables.
If you’ve enjoyed the series on orchids of Manitoba, you might like to visit the site of Manitoba’s Native Orchid Conservation Inc., a non-profit organization whose purpose is “to protect unique mini-ecosystems and their plant communities. This primarily involves native orchids but can also extend to other rare and/or endangered plants”. Their web site contains many additional photographs of Manitoba orchids and their Orchids of Manitoba: A Field Guide is an excellent resource if you can’t resist top-notch field guides (like me).