This section is from the book "Handbook Of Hardy Trees, Shrubs, And Herbaceous Plants", by W. Botting Hemsley. Also available from Amazon: Handbook of hardy trees, shrubs, and herbaceous plants.
Terrestrial herbs with tuberous or fascicled roots and sheathing radical or sessile cauline leaves; or, as in most of the tropical species, epiphytes, with enlarged stems called pseudo-bulbs. Flowers solitary, spicate, racemose or paniculate. Perianth coloured, superior, composed of 6 irregular segments. The 3 outer are similar, and also the 2 lateral inner, whilst the lower inner segment, usually termed the labellum, assumes a variety of curious forms, and is often spurred at the base.
Stamens and style confluent. Anther 1 and opposite the lip, or (in Cypri-pedium) 2 and opposite the lateral inner lobes of the perianth; pollen cohering in 2, 4, or 8 waxy or granu-liferous masses. Fruit a 1-celled 3-valved inferior twisted capsule, containing numerous very minute seeds attached to the valves. This order includes upwards of 400 genera comprising 3,000 species, abounding in all climates except the extreme cold. We have about 40 indigenous species belonging to 18 different genera. Like the majority of the terrestrial species they are more curious than beautiful, and as they hardly come within our limits, and more space than we can afford would be required to give intelligible de-scriptions, we must be content with mentioning the names of a few of the more interesting species. Foremost come the common Spring-flowering species of Orchis, O. mas-cula and Morio which throw up their spikes of purplish flowers from April till June. The handsomest perhaps of the genus is O. pyramidalis which has rosy-crimson or reddish flowers towards the end of Summer. The Bee Orchis, Ophrys apifera; Fly Orchis, 0. muscifera; and the Spider Orchis, C. aranifera, are so named from the resemblance their flowers bear to those insects. The Helleborines, Cephalanthera, have leafy stems and white or rosy flowers. C. grandiflora, with large white flowers, is a very conspicuous plant in copses on a chalky soil. A very common species is the Twayblade, Listera ovata, a plant about 18 inches high, with two opposite oval ribbed leaves, from between which springs a long slender raceme of yellowish-green flowers. None of these plants are of easy culture, and perhaps the terrestrial less so than the epiphytes, of which there are no hardy species. But still some careful gardeners contrive to grow some of them successfully, such as the Lady's Slipper, Cypripedium Calceolus (fig. 226), a rare indigenous plant with reddish-brown and yellow flowers, found in two or three localities only in the North of England. There are several more showy North American species; as C. guttatum, purplish-violet spotted and edged with white; C. cdndidum, white; C. spectdbile, white tinged with purple, etc.
Fig. 226. Cypripedium Calceolus. (1/3 nat. size.)