They're very pretty! But I'm lost here. What is the difference between the american Cypripedium parviflorum, and the european Cypripedium calceolus? I see no difference between the two. I also thought that the american one was called Cyp calceolus var parviflorum.

Camille, they're the same plant :) The taxonomic nomenclature has changed. Cyp calceolus was the former name. Now it's known as Cypripedium parviflorum. In the USA there are two varieties of the plant: Cypripedium parviflorum (lesser/small flowered) and Cypripedium pubescens (greater/large flowered

Also, these are very beautiful and look very happy :) can I ask where you got them? I was at a MN Orchid Society sale a couple months ago and Jim Bull from Winsome Orchids was selling Cyp pubescens and reginae for $20 bucks!!! I didn't think I would be able to grow them (or keep them from the deer), though, so I passed up the great deal...Also, how are you growing them, are they just in your garden soil?

Anthony,
More correctly the two varieties are Cyp. parviflorum var. makasin and Cyp. parviflorum var. pubescens. You are correct that var. pubescens has larger flowers but the best identifying characteristics is that var. makasin has a much stronger fragrance and var. pubescens has a densely hairy lower sheathing bract (outer surface). Generally var. makasin has darker petals than var. pubescens, but that is not always the case.

I looked at the USDA site again and you're correct :) the variety in the northern USA is makasin, the southern variety is parviflorum and the other is pubescens. Thanks for alerting me to that! Do you know if there is much difference between the northern and southern varieties?

Anothony,
For clarity and for those who might have difficult following this the three varieties are:
-Cyp. parviflorum var. pubescens (Large-flowered LS)
-Cyp. parviflorum var. makasin (Northern Small-flowered LS)
-Cyp. parviflorum var. parviflorum (Southern Small-flowered LS)
Many still consider var. makasin as a synonym of Cyp. parviflorum var. parviflorum and recognize only two varieties, the above and Cyp. parviflorum var. pubescens (formerly Cyp. calceolus). It is sometime hard to tell vars. makasin (Northern Small-flowered) and pubescens (Large-flowered) apart and even more difficult to tell the difference between the two small-flowered varieties. The chief difference, as I understand it, between the two small flowered vars., makasin and parviflorum is that makasin grows in calcareous wetlands and is very heavily scented, while parviflorum grows in neutral to acid woodlands and is very lightly scented. The difference in habitat, then, is the main thing.