Cypripedium calceolus

Cypripedium calceolus is the most spectacular and well-known terrestrial orchid in Europe. This Lady's Slipper, which has become rare in its natural habitat, can still be found in a few rare locations in the Alps or other mountain ranges. Its large flowers are made up of long chocolate-coloured sepals and a prominent petal (the lip) straw yellow in the shape of a slipper. This demanding species acclimates more easily in alpine gardens where it finds a favourable climate and soil. 

Cypripedium calceolus is a botanical species of cool temperate climates that experience cold winters and cool, slightly humid summers. In terms of soil, this plant grows in the humus that has formed on and between limestone rocks, in the morning sun or in partial shade. Slugs and snails are also enemies of this Lady's Slipper. Like all orchids, it belongs to the orchid family.

This orchid has a perennial suckering stump. Its thick underground rhizome lengthens and divides over the years, allowing the plant to spread in colonies. Its roots penetrate deeply into the soil. They are mycorrhizal, meaning they live in symbiosis with specific fungi. The deciduous vegetation, absent in winter, emerges from the ground between April and May. This Cypripedium calceolus forms small clumps of 2 to 6 leafy shoots reaching about 45cm (18in) in height. Each hairy stem bears 3 to 5 sheathing leaves at the base, broadly ovate, marked by strong parallel veins, light green in colour, slightly hairy on the underside. Flowering occurs between May and July, earlier or later depending on the climate and the year. Each individual produces only one or two flowers, in the axil of bracts. Each flower, which can measure up to 10cm (4in) wide, consists of 3 sepals and 3 petals. These petals are elongated, tapered, lanceolate in shape, slightly twisted. Their colour varies from reddish-brown to chocolate brown. The swollen lip, in the shape of a 'slipper', is straw yellow with brown spots. The fruit is a capsule that can persist on the plant for a year.

Cypripedium calceolus is a typically montane species, very hardy. It cannot tolerate heat or drought. If your climate allows, plant it in partial shade in a limestone rockery, between rocks or at the edge of a leafy woodland, in well-aerated humus that remains slightly moist in summer. This collector's plant can be associated with alpine perennial geraniums or ferns, for example. Avoid associating it with too vigorous plants that could suffocate or hinder its growth.

Handle your orchids with care when you receive them: these plants produce few roots and are delicate!