Cypripedium calceolus Seeds | Lady’s Slipper Orchid
LATIN NAME: Cypripedium calceolus
COMMON NAME: Lady’s Slipper Orchid
Plant Profile
The pouch is a modified lip, the labellum, folded into a slipper with an infolded rim. Its inner surface is smooth and the only exit is a pair of narrow openings beside the staminode, placed so that the bee must pass the anthers and the stigma as she climbs out.
Cypripedium calceolus is listed in Appendix I of the Convention on International Trade in Endangered Species, the strictest category, and it is protected by law through most of its European range. The listing exists because the species was dug up and traded for a century. Any plant offered for sale should be nursery-propagated material with paperwork.
An orchid capsule holds an enormous number of seeds, and a single slipper capsule can carry many tens of thousands of them. That is the compensation for the fact that almost none will find both a suitable fungus and a suitable site at the same moment. The capsule splits along three seams and releases its contents to the wind.
Science & Biotechnology
Terrestrial orchid seed can be raised without a fungus, on an agar medium that supplies the sugars and minerals the seed cannot provide. The classic formulation is Knudson C, and most modern media follow the same pattern with added vitamins and a thin layer of activated charcoal to reduce the browning that kills cultures. The seed is surface-sterilised, sprinkled on the medium and left in darkness until the tiny green protocorms appear.
Uses & Benefits
The usual visitors are small solitary bees, above all Andrena species, with occasional sweat bees. They enter head-down, fail to climb the walls, and escape under the staminode within minutes. Pollen is held in sticky masses rather than as loose dust, so it clings to the bee’s back where she cannot easily groom it off.
Because the flower offers no reward, many bees learn to avoid slipper orchids after a single visit, and the proportion of flowers that set seed in the wild is low. The result is a plant that invests heavily in a few large, long-lived flowers and reproduces slowly,.
Growing from Seed
An orchid seed is a dust particle: a thin testa around an undifferentiated embryo, with no endosperm to feed the seedling in the ordinary way. Sprouting therefore requires a fungus. The partner colonises the embryo and passes carbon and nutrients to the seedling, and in terrestrial slipper orchids the fungi involved are typically rhizoctonia-type partners, including Tulasnella and Ceratobasidium species.
A mature clump can be lifted in early spring and divided with a knife, keeping at least two growing eyes on each piece, and the divisions replanted at the same depth. This is how a cultivar is kept true, because seed-raised plants are not clonal.
Seedlings lifted from the flask have soft, unhardened tissue and no reserves. Wash the agar off the roots, plant into a sterile mix of fine bark, perlite and coarse leaf mould, and keep them under high humidity with gentle air movement for the first season.
Plant out into dappled shade and a soil that never dries completely but never waterlogs: ordinary garden soil, coarse leaf mould and grit suits it well, with a mulch of leaf litter each autumn. Because the plant depends on soil fungi, a site that has been sterilised or deep-dug is the wrong place for it.
Slugs take the young shoots before they open, and a late frost can blacken a shoot that pushed too early in a mild spring. Both are best handled by an open, airy position and coarse grit around the crown rather than by chemical means. Mature plants can be left undisturbed for years; the commonest cause of failure is a gardener who digs the clump up to see how it is doing.
Our Take
Grow this orchid from nursery-propagated stock or from a flask, never from a wild plant, and give it a place you do not intend to dig again. The same laboratory technique will raise other orchids, and a flask of Dendrobium officinale is a good place to learn sterile handling before you attempt a terrestrial species. For a woodland companion, the saprophytic Gastrodia elata is grown on a fungal substrate rather than on soil.
Related Reading
If Lady’s Slipper Orchid appeals to you, these related plants are worth a look: