The Fairy Slipper, Calypso bulbosa, has two American varieties, The Western Fairy Slipper, variety occidentalis, and the Eastern Fairy Slipper, variety americana. There are two other varieties also, variety bulbosa, found in Europe and Asia, and variety speciosa, found in Japan, but neither of these is found in North America and are not the subject of this post.
The two native varieties' Latin names reflect their distribution, but the English names do not. The Western Fairy Slipper is found only in the far west and is well named "occidentalis." The Eastern Fairy Slipper is found all across northern North America except for a small area in the far west along the Pacific Coast and is better named "americana" than "Eastern."
The Eastern Fairy Slipper is easily distinguished by the yellow beard in the center of the lip and by the lack of brown spotting on the central lobe of the lip. It has several forms, a white-flowered form, forma albiflora (not shown here - we've not seen it), a pink-flowered form also shown below, forma rosea, and a two-flowered form, forma biflora.
Calypso bulbosa var. americana
Calypso bulbosa var. americana fma. rosea
The Western Fairy Slipper tends to be somewhat taller and is not as vividly colored as the other variety. It has a white beard and heavy brownish-purple spotting. This spotting varies in intensity and color, as does the pink color of the rest of the flower, which can be a very deep lavender-pink or a pink so pale it is nearly white. It has only one form, a pure white form, forma nivea.
Calypso bulbosa var. occidentalis
Calypso bulbosa var. occidentalis fma. nivea
There is also a very rare hybrid between the two species, Calypso bulbosa x kostiukiae. It is named after its discoverer and has the yellow beard of the eastern Fairy Slipper and a finely spotted lip that comes from the Western Fairy Slipper. We finally found this hybrid in a location where it had been reported and where we had looked several years in a ro.
Calypso bulbosa x kostiukiae
Besides these varieties and forms there is considerable color variation in the flowers, especially of the Western Fairy Slipper. They vary from the very intensely colored flowers to near-albinos as shown below. The near-albino is clearly that for the lack of spotting on the lip and the nearly yellow color at the back of the pouch, where the flower is normally a brownish-purple.