Cypripedium parviflorum is an extremely variable species and is treated here as comprising four varieties. They all have the same medicinal uses The four varieties are:-
Cypripedium parviflorum parviflorum. Native to eastern, southeastern and central southern states of the USA.
Cypripedium parviflorum var. exiliens Sheviak. Restricted to Alaska.
Cypripedium parviflorum var. makasin (Farw.) Sheviak. Found in most of Canada and northern states of the USA
Cypripedium parviflorum var. pubescens (Willd.) O.W.Knight. Found in most of Canada, northern, eastern and central USA

Common Name: Nerve Root

General Information

Cypripedium parviflorum is a herbaceous perennial plant growing from a fleshy rootstock with short rhizomes; it slowly spreads to form a clump with leaves arisng from the rhizomes and flowering stems around 70cm tall[, ].
With a high reputation as an effective sedative and nervine, this plant has been heavily harvested from the wild in the past for use as a medicine and was also gathered for horticultural purposed. It is less used medicinally (though no less effective) and is still grown as an ornamental in gardens.
Cypripedium parviflorum is confined to North America with a large distribution area and abundant populations. There are currently between 81 and about 300 occurrences and a population trend decrease is suspected due to numerous threats. Although there are threats to the species and its habitats these are unlikely to cause the population to decline quickly in the near future so long as conservation measures are adopted. The plant is classified as 'Least Concern' in the IUCN Red List of Threatened Species(2014)[].

Known Hazards

Especially during the flowering season, the glandular hairs on the leaves and stems can cause a rash, similar to poison ivy rash[, ]. The irritation is usually minor, or only lasts for a few minutes[].
It has been stated that the roots may cause psychedelic reactions, and large doses may result in giddiness, restlessness, headache, mental excitement and visual hallucinations[].

Botanical References

,

Range

Most of Canada and the USA, excluding northeast Canada (Nunavut), southern central to southwest USA, and Florida.

Habitat

Mountain meadows, mesic places in Ponderosa Pine, mixed conifer, aspen forest communities, non-sphagnum bogs, marshes, wet prairies, rocky wooded hillsides and mixed woodland ; mostly at elevations up to 1,200 metres, sometimes to 2,900 metres[, ]

Properties

Conservation Status	Least Concern
Medicinal Rating
Habit	Perennial
Height	0.60 m
Pollinators	Bees, Insects
Self-fertile	Yes
Cultivation Status	Ornamental, Wild

Cultivation Details

Cypripedium parviflorum is a very cold-tolerant plant, when fully dormant it can withstand temperatures down to about -25°c[].
Found in the wild on moderately moist to dry substrates, confined to predominantly calcareous stony soils, rich in humus, with basic, neutral, to acidic pH soil, favouring shaded, cool, north-facing and well-drained slopes[]. Succeeds in shade or full sun so long as there is adequate moisture[]. Grows well in a woodland garden[]. Plants are best grown on a north or north-west aspect in order to slow down early growth[]. Requires a humus rich soil with plenty of moisture in the growing season[], it also succeeds in chalky soils[]. Must not be planted too deeply[].
A very ornamental plant[] it is long-lived when once established, though it is very difficult to establish a plant[]. The flowers have a soft, rose-like perfume[]. Plants are growing very well at the Savill Gardens in Windsor[].
This plant is becoming rarer in the wild due to overcollecting for medicinal usage[]. Reports that the plant is cultivated for its medicinal uses are largely spurious and, unless you can be certain that the root has come from a cultivated source, it is best not to use this plant medicinally but to use suitable substitutes such as Scutellaria laterifolia and Lavendula angustifolia[].
Cypripedium parviflorum is an extremely variable species, reflecting individual phenotypic plasticity, infraspecific differentiation, and hybridization with related species. In particular, var. pubescens is difficult to delimit. In exposed situations, especially in calcareous soils, plants are low-growing with ascending, often narrow leaves and rather small flowers; in exposed boreal and arctic sites, plants and flowers may be very small with scarcely spiraled to flat petals. Such plants from Newfoundland were originally described as Cypripedium parviflorum var. planipetalum. When transplanted to less severe conditions however, those plants often develop into larger plants with larger flowers of more common form; indeed, the holotype sheet of var. planipetalum includes a range in habit and floral morphology and includes a plant rather typical of the boreal var. pubescens[].
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 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

Nerve root has a high reputation for its sedative and relaxing effect on the nervous system[, ]. Fluidextractum Cypripedii, U.S.P. which is an
extract ofthis plant, was an official medicine, included in the United States Pharmacopeia and also in the British Pharmaceutical Codex until the early 20th century[].
The root is a pungent bitter-sweet herb with an unpleasant odour. It was much used by the North American Indians who used it as a sedative and antispasmodic to ease menstrual and labour pains and to counter insomnia and nervous tension[, ].
The root is antispasmodic, diaphoretic, hypnotic, nervine, sedative, tonic[, , , , , ]. It is taken internally in the treatment of anxiety, nervous tension, insomnia, depression and tension headaches[]. The active ingredients are not water soluble and so the root is best taken in the form of a tincture[]. The plant is said to be the equivalent of Valerian (Valeriana officinalis) in its effect as a nervine and sedative, though it is less powerful[, ]. Another report says that its restorative effect appears to be more positive than that of valerian[].
Traditionally, a root tea was used to treat worms, stomach ache, flu and neuralgia[].
The roots are harvested in the autumn and are dried for later use[].
In the interests of conservation, it is best not to use this herb unless you can be certain it was obtained from a cultivated source - see the notes above under cultivation details[].

The roots are used in homoeopathy. They are said to be an efficient antidote for the skin symptoms caused by contact with poison ivy (Rhus species, Toxicodendron species). It is also used in treating a range of conditions, including nervousness in children; from teething and intestinal troubles; debility after gout; hydrocephaloid symptoms; the result of long, exhausting diarrhoea; sleeplessness; cerebral hyperasthesia in young children often as the result of overstimulation of the brain[].

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[].