In place of the six stamens we commonly find but one (two in Cypripedium), and that one is raised together with the stigmatic surfaces on an elongation of the floral axis known as the "column."
In Cypripedium all three stigmas are functional, but in the great majority of orchids only the lateral pair form receptive surfaces (st, fig.
It contains two small genera of tropical Asia and Africa with almost regular flowers, and the large genus Cypripedium containing about 80 species in the north-temperate zone and tropical Asia and America.
In Cypripedium two stamens are present, one on each side of the column instead of one only at the top, as in the group Monandreae, to which belong the remaining genera in which also only two stigmas are fertile.
In Cypripedium two of the outer stamens are wanting; the third - the one, that is, which corresponds to the single fertile stamen in the Monandreae - forms a large sterile structure or staminode; the two lateral ones of the inner series are present, the third being undeveloped.
The order is well represented in Britain by 18 genera, which include several species of Orchis: Gymnadenia (fragrant orchis), Habenaria (butterfly and frog orchis), Aceras (man orchis), Hermin- ium (musk orchis), Ophrys (bee, spider and fly orchis), Epipactis (Helleborine), Cephalanthera, Neottia (bird's-nest orchis), one of the few saprophytic genera, which have no green leaves, but derive their nourishment from decaying organic matter in the soil, Listens (Tway blade), Spiranthes (lady's tresses), Malaxis (bog-orchis), Liparis (fen-orchis), Corallorhiza (coral root), also a saprophyte, and Cypripedium (lady's slipper), represented by a single species now very rare in limestone districts in the north of England.
Nearly all the species of plants which grow on these prairies are common to Europe (paeonics, Hemerocallis, asters, pinks, gentians, violets, Cypripedium, Aquilegia, Delphinium, aconites, irises and so on), but here the plants attain a much greater size; a man standing erect is often hidden by the grasses.
The bottom of the border as well as that Cymbidium Cypripedium Cyrtopodium Dendrobium Diacrium Disa Epidendrum Eulophia Eulophiella Galeandra Gongora Grammatophyllum Habenaria Houlletia lonopsis Ipsea Laelia Laelio-Cattleya* Leptotes Lissochilus Lycaste Masdevallia Miltonia Mormodes Odontoglossum Odontioda* Oncidium Peristeria Pescatorea Phaj us Phaio - calanthe* Phalaenopsis Pilumna Platyclinis Pleione Pleurothallis Polystachya Promenaea Renanthera Restrepia Rodriguezia S accolabium Schomburgkia Scuticaria Sobralia Sophro-cattleya* Sophronitis Spathoglottis Stanhopea Thunia Trichopilia Trichosma Vanda Zygo - colax* of the drain must be kept lower than the general level of the subsoil, else the soakage will gather in all the little depressions of its surface.
In some orchids, as Cypripedium, the pollen has its ordinary character of separate grains.
This arrangement may be understood by reference to the following diagram, representing the relative position of the stamens in orchids generally and in Cypripedium.