Common Name: White Lady's Slipper

General Information

Cypripedium candidum is a herbaceous perennial plant, spreading slowly to form a clump; it produces 3 - 4 (occasionally 5) leaves on each erect flowering stem around 11 - 40cm tall[].
The plant is harvested from the wild for use as a medicine. It is grown as an ornamental.
Cypripedium candidum is scattered widely across North America, and is most abundant in Minnesota with some subpopulations containing over hundred individuals, but it is less common elsewhere. The population trend is decreasing and the species is extinct in Pennsylvania and possibly Saskatchewan, Missouri and New Jersey. The species is under numerous threats especially habitat loss, agriculture intensification, herbicide application, loss of pollinators, clear-cutting, invasion of woody shrubs and exotic species, hydrological alterations, land drainage, drought, infrastructure development, collection and peat or marl mining activities, which cause a continuing decline of the species on all the estimated locations and the destruction of some subpopulations. It is estimated that the species currently occurs in eight threat defined locations and these are increasingly becoming severely fragmented. The plant is classified as 'Vulnerable' in the IUCN Red List of Threatened Species(2014)[].

Known Hazards

We have no specific reports for this species but, especially during the flowering season, the glandular hairs on the leaves and stems of some N. American members of this genus can cause a rash, similar to poison ivy rash[, ]. The irritation is usually minor, or only lasts for a few minutes[].
We have no specific information for this species, but it has been stated that the roots of at least one member of the genus may cause psychedelic reactions, and large doses may result in giddiness, restlessness, headache, mental excitement and visual hallucinations[].

Botanical References

Range

Eastern and central N. America - Saskatchewan to Ontario, south to Nebraska, Missouri, Kentucky and Maryland. Also in Alabama

Habitat

Mesic to wet prairies and fen meadows, very rarely open wooded slopes; at elevations from 70 - 700 metres[].

Properties

Conservation Status	Vulnerable
Medicinal Rating
Habit	Perennial
Height	0.25 m
Pollinators	Bees, Insects
Self-fertile	Yes
Cultivation Status	Ornamental, Wild

Cultivation Details

Cypripedium candidum is a cold-tolerant plant, when fully dormant it can withstand temperatures down to about -20°c[].
Prefers a position in full sunlight in moist to dry calcareous and sandy substrates (calcium-rich, or alkaline)[].
Orchids are, in general, shallow-rooting plants of well-drained low-fertility soils. Their symbiotic relationship with a fungus in the soil allows them to obtain sufficient nutrients and be able to compete successfully with other plants. They are very sensitive to the addition of fertilizers or fungicides since these can harm the symbiotic fungus and thus kill the orchid[].
The plant begins blooming while the shoots are still emerging from the soil; at that time they are small, with the leaves clustered near the base. The plants enlarge greatly during and after anthesis, and the leaves may assume a more median position[].
The flowers of Cypripedium species belong to the group of 'trap' flowers. An insect as it crawls in, can only escape from the slipper-like labellum through a tunnel near the base of the labellum from where it is directed first to the nearby stigma where possible pollinia from another flower on its back are stripped off and while escaping, sticky pollen from the nearby anthers adhere to its back for the pollination of another flower[].

Edible Uses

None known

Medicinal

An extract from the roots of the species was used historically used as a sedative and treatment for nervous disorders and insomnia[].

Other Uses

None known

Propagation

Seed - surface sow, preferably as soon as it is ripe, in the greenhouse and do not allow the compost to dry out. The seed of this species is extremely simple, it has a minute embryo surrounded by a single layer of protective cells. It contains very little food reserves and depends upon a symbiotic relationship with a species of soil-dwelling fungus. The fungal hyphae invade the seed and enter the cells of the embryo. The orchid soon begins to digest the fungal tissue and this acts as a food supply for the plant until it is able to obtain nutrients from decaying material in the soil[]. It is best to use some of the soil that is growing around established plants in order to introduce the fungus, or to sow the seed around a plant of the same species and allow the seedlings to grow on until they are large enough to move.
Division with care in early spring, the plants resent disturbance[]. Remove part of the original rootball, making sure to keep some of the soil around it intact[].
Division is best carried out towards the end of the growing season, since food reserves are fairly evenly distributed through the rhizome[]. Small divisions of a lead and two buds, or divisions from the back (older) part of the rhizome without any developed buds, establish quickly using this method[]. Replant immediately in situ[].