Read about Orchidaceae in the Standard Cyclopedia of Horticulture
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Orchidaceae (from the genus Orchis, an ancient name of these plants). Orchid Family. Fig. 13. Herbaceous plants of very diverse habit and structure; terrestrial, epiphytic or saprophytic, sometimes climbing; the terrestrial with fibrous roots or with thickened tuber-like roots, the epiphytic often with the base of the leaf and adjoining stem swollen, forming a pseudobulb; the saprophytic without chlorophyll; the epiphytic often with aerial hanging roots are provided with a water-absorbing layer (velamen): leaves alternate, succulent, coriaceous or membranous, linear to oval: flowers bisexual, rarely unisexual, irregular, epigynous; perianth of 6 parts, in 2 series, usually all petaloid; one petal larger, forming the lip (labellum); stamens originally 6, but all except 1 or 2 wanting, or reduced to staminodia, united with the pistil; pollen-grains compound, granular, or aggregated into masses (pollinia) which are either free in the anther or attached by a stalk to a viscid apical or stigmatic gland; carpels 3; ovary inferior, 1- or 3-celled; ovules very numerous; style united with the stamens to form the column; stigma in the front of the column, or on a projecting lobe: fruit a capsule; seeds very minute. This is an important family of more than 400 genera and between 6,000 and 10,000 species. Orchids are very widely distributed, except in the arctics, but are most numerous in the tropics. Those of temperate regions are mainly terrestrial; those in the tropics commonly epiphytic. The large genera are Epidendrum, 500 species; Habenaria, Dendrobium, Bulbophyllum, and Oncidium, 200-600 species each; Masdevallia, Odontoglossum, and Maxillaria, each 100 or more species. From the standpoint of the intricate and very special mechanisms evolved in order to insure cross-pollination, the orchids are the most wonderful of our insect-pollinated plants, for a detailed account see Darwin's "Fertilization of Orchids," or Kerner and Oliver's "Natural History of Plants." In general, the insect visiting the showy flower for the honey comes in contact with the sticky gland above the stigma, thereby pulling it out, along with the attached pollen masses. While the insect is going to another flower, the pollen masses dry and bend down until they are in position to strike the viscid stigma, which tears away and retains some of the pollen. The method of pollination in Cypripedium is fundamentally different. Some orchids (e.g., Catasetum) possess a sensitive explosive mechanism that forcibly ejects the pollen mass, often to the distance of 2 or 3 feet. The minute seeds of the orchids are well adapted to be disseminated by the wind and find lodgment in the crevices of the bark of trees and on other supports. Orchids are divided into large groups as follows: Group I. Diandrae. The two lateral stamens of the inner whorl fertile, the dorsal of the outer whorl staminodial or fruitful, the others absent. Cypripedium, Selenipedium, Paphiopedilum, and others. Group II. Monandrae. The dorsal stamen of the outer whorl fruitful, all the others wanting. By far the majority of the species belong here. Subgroup I. Pollinia connected by caudicles with a gland at base of anther near stigma. Subgroup 2. Pollen without caudicles or with these attached to a gland at apex of anther. The family is very distinct and easily distinguished. Its only near relatives are the Burmanniaceae. The peculiar structure of the stamens and pistil, together with the minute exalbuminous seeds are distinctive. The Orchidaceae is perhaps the most important family from the standpoint of ornamental gardening. To grow these singular, fantastic, showy, and often sweet-scented flowers has in recent years become almost a craze. It is estimated that, whereas Linnaeus knew but a dozen exotic orchids, at the present day more than 2,500 are known to English horticulturists. Plants in the family useful for other purposes are few. The most important is vanilla, derived from the capsule of Vanilla planifolia of Mexico, and now widely cultivated in the tropics. Faham (Angraecum fragrans of Bourbon) has a fragrant, bitter-almond-like taste: the leaves are used for indigestion and tuberculosis, and are known as Bourbon tea. Salep is derived from the roots of various terrestrial orchids of the Mediterranean region. The roots of helleborine (Epipactis latifolia) are used for rheumatism. The root of Spiranthes diuretica of Chile is renowned as a diuretic. The flowers of Habenaria conopsea are used for dysentery. Spiranthes autumnalis and Habenaria bifolia are said to be aphrodisiac. The roots of Cypripedium parviflorum var. pubescens are frequently used in America as a substitute for valerian.CH
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Genera
The taxonomy of this family is in constant flux, as DNA studies give new information.
Subfamilies
The following genera have been described (for a full list, see List of Orchidaceae genera with more than 800 genera and many pictures):
Aa; Abdominea; Acampe; Acanthephippium; Aceratorchis; Acianthus; Acineta; Acrorchis; Ada; Aerangis; Aeranthes; Aerides; Aganisia; Agrostophyllum; Amitostigma; Anacamptis; Ancistrochilus; Angraecum; Anguloa; Ansellia; Aorchis; Aplectrum; Arethusa; Armodorum; Ascocenda; Ascocentrum; Ascoglossum; Australorchis; Auxopus; Baptistonia; Barbrodia; Barkeria; Barlia; Bartholina; Beloglottis; Biermannia; Bletilla; Brassavola; Brassia; Bulbophyllum; Calypso; Catasetum; Cattleya; Cirrhopetalum; Cleisostoma; Clowesia; Coelogyne; Coryanthes; Cymbidium; Cyrtopodium; Cypripedium; Dactylorhiza; Dendrobium; Disa; Dracula; Encyclia; Epidendrum; Epipactis; Eria; Eulophia; Gongora; Goodyera; Grammatophyllum; Gymnadenia; Habenaria; Herschelia; Laelia; Lepanthes; Liparis; Ludisia; Lycaste; Masdevallia; Maxillaria; Mexipedium; Miltonia; Mormodes; Odontoglossum; Oncidium; Ophrys; Orchis; Paphiopedilum; Paraphalaenopsis; Peristeria; Phaius; Phalaenopsis; Pholidota; Phragmipedium; Platanthera; Pleione; Pleurothallis; Promenaea; Pterostylis; Renanthera; Renantherella; Restrepia; Restrepiella; Rhynchostylis; Saccolabium; Sarcochilus; Satyrium; Selenipedium; Serapias; Sophronitis; Spiranthes; Stanhopea; Stelis; Thrixspermum; Trias; Trichocentrum; Trichoglottis; Vanda; Vanilla; Zeuxine; Zygopetalum.
Gallery
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Pseudobulbs of an epiphytic orchid]
Calopogon orchid
Wild orchid from Sumatran Rainforest
Bumblebee Orchid (Ophrys bombyliflora)
cross-section of an orchid capsule, showing 3 or 6 longitudinal slits
An orchid seed capsule
Phalaenopsis hybrid
Vanilla fruit
References
- Standard Cyclopedia of Horticulture, by L. H. Bailey, MacMillan Co., 1963
External links
- w:Orchidaceae. Some of the material on this page may be from Wikipedia, under the Creative Commons license.
- Orchidaceae QR Code (Size 50, 100, 200, 500)