Calypso bulbosa / eastern fairy-slipper

Adjectives: clonal, dramatic, interesting bits, native, showy, undisturbed

Synonym: Cypripedium bulbosum

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Fairy slippers  are startling when you spot them. They are small, but so impressive that you can’t help but stop and look. I can’t imagine getting tired of them. Sometimes, you just see one or two. Other times, you find them in patches by the dozens.

In any case, each plant has but a single basal leaf 1-2 inches long, produced in the autumn. The leaf is pleated along parallel veins and wrinkled. It originates from a corm about the “size of an average fingernail” (although I have never previously thought on what an average fingernail is). It remains right at ground level and only lasts through the spring until the plant is done flowering. Following anthesis (pollination), the leaf withers. A nodal region of the corm gives rise to a new shoot bud, which will become the new corm. These build up… previous years’ corms remain in sequence, for a string representing up to 2 to 4 years.

In mid to late spring, a solitary, nodding flower (rarely 2) is produced. In 2020 in the Valley, I began seeing them in early June. The flowers are usually pink, magenta, or white, with two petals and three sepals nearly identical in size splayed out in a star-like pattern.  Each is pointy. A narrow, sharply pointed floral bract stands erect behind the flower.

The bit that really says “orchid!” is an oval, pouch- or slipper-like labellum at the bottom of the flower. This is a modified third petal. It is lined with veins of maroon and purple, with dotted edges and bears a number of yellow hairs on the upper surface. The labellum is lighter color than the lateral petals and sepals.

Fairy slipper flowers are monoecious but can not self pollinate;  bumblebees are needed to carry the pollen flake (pollen sac) between plants. Each flower has a large number of ovules, but a single pollen flake carries enough pollen to result in anywhere from 80 to 20,000 very small seeds. While seedlings are fairly common in the west, the perpetuation of colonies reflects sprouting from the corms.

Technically, the fairy slipper in the Valley is var americana, distinguished from var occidentalis by the lack of stripes or spots on the labellum. It seems odd that this is “eastern” fairy-slipper, as it is (or was) found throughout most of the northern US and Canada. But occidentalis is limited to the far northwest, so it is more western, I guess. Interestingly, the USFS site says that americana is NOT found in Idaho. But it is, and is not all that rare. Earle and Lundin also only illustrate var occidentalis so that is apparently the prevalent form in northern and western Idaho.

Even more interesting bits – The genus Calypso was split off from the genus Cypripedium and contains only this one species.

In most of North America, Calypso is found in wet coniferous or mixed forests and bogs; in the northwest, it may also be found in drier, shady coniferous forests. In the Valley, it seem to show up where least expected, but always in shaded spots.

Although fairy slippers are terrestrial orchids (as opposed to epiphytic), they are not really living in soil. Rather, they live in a thin layer of humus (decaying organic matter) overlying the soil, or on moss covered humus in bog environments. They also can’t live without a symbiosis with mycorrhizal fungi. And… the flower structure is so complex that pollination requires specialized insects. And… the environment required for seed germination is also demanding.

The bottom line of all this is that  fairy slippers are endangered or extirpated in much of their range, much of that due to collectors and sellers. Even if they appear common in Idaho, they are almost impossible to transplant. Don’t try. Enjoy them where they are and be happy that you have the memory.

One more thing… it has been said that “scientists are still uncertain as to whether fairies do in fact, steal away with the petals in the night and dance!” (ref) While that question would have naturally occurred to any child, I had never thought of it before. I will now.