The different genera are distinguished, partly by the manner in which the granules of the pollen adhere together, and partly by the shape of the flowers; and their different species vary principally in the form of the labellum. In the genera Orchis and Habenaria, the labellum is drawn out behind into a kind of spur (see _e_ in _fig._ 146); and in others it assumes strange shapes, as in the Man Orchis (_Aceras anthropophora_), where the labellum looks like a little man; and in the Lizard Orchis (_A._ or _Orchis hircina_) where the labellum is drawn out into a long tail, which looks like the tail and long body of the lizard, while the petals, which are long and narrow and bent back, look like the hind legs. In the genus Ophrys, the labellum also takes strange shapes, sometimes resembling a bee, at others a fly, and at others a spider. In the genus Cypripedium, the two side stamens bear anthers and pollen, and only the central one is imperfect.
In the orchideous epiphytes the same general construction prevails, but the forms of the flowers are still more varied and fantastic. All of them have pseudo bulbs above ground, which serve as substitutes for the tubers of the terrestrial species.
This order contains several plants, well known for their useful properties, as for example, the Ginger (_Zingiber officinale_), and the Turmeric (_Curcuma Zerumbet_). Some of the plants grow tall and reed-like, as for example in Hedychium. Most of the genera have a creeping underground stem, called a rhizoma, which is often jointed. The flowers are produced in spathe like bracts; the calyx is tubular, and adheres to the ovary; and the corolla, which is also tubular, has six segments arranged in two rows; the inner row, which is supposed to consist of the dilated filaments of abortive stamens, has one of the segments, called the labellum, larger than the rest. There are three stamens, two of which are abortive, as in the Orchidaceæ; but the pollen does not cohere in masses, and it is not inclosed in a kind of pouch or bag. The ovary is three-celled (though the cells are sometimes imperfect), and many-seeded; the style is filiform, and the stigma is dilated and hollow. The fruit is generally a capsule; but in some cases it is a berry.