I live in the amazing, orchid rich state of Minnesota. These Lady Slippers are from a calcareous fen near one of our major rivers. The site is about 70 acres. About half of that 70 is high quality fen, with the remaining half being colonized by invasive, reed canary grass and common reed grass (though there is still a good deal of native plant diversity even in the disturbed/lower quality areas).
Regardless, there are quite a few patches of Cypripedium candidum growing here. Cyp candidum is on the list of Special Concern Species in Minnesota. Last year, I found several dozen (maybe 50) clumps in this particular fen. This year I found about 20. It's been a dry year, though and we got a late season freeze that blasted many of the buds on several of the plants.
The unfortunate aspects aside, calcareous fens are quite lovely places to visit. I've also seen Cyp. parviflorum (pubescens and parviflorum), Cyp. reginae, Spiranthes, Platanthera, and Liparis at the site.
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