The World Flora Online

SELECTED REFERENCES

Bentley, S. L. Native Orchids of the Southern Appalachian Mountains. Chapel Hill. Brown, P. M. 1997. Wild Orchids of the Northeastern United States: A Field Guide. Ithaca, N.Y. Brown, P. M. 2000. The Florida Native Orchid Project. Palmetto 20: 6–10. Brown, P. M. 2002. Wild Orchids of Florida. Gainesville. Burns-Balogh, P. and V. A. Funk. 1986. A phylogenetic analysis of the Orchidaceae. Smithsonian Contr. Bot. 61. Case, F. W. 1987. Orchids of the western Great Lakes region, rev. ed. Bull. Cranbrook Inst. Sci. 48. Coleman, R. A. 1995. The Wild Orchids of California. Ithaca, N.Y. Correll, D. S. 1950. Native Orchids of North America North of Mexico…. Waltham, Mass. Dressler, R. L. 1981. The Orchids: Natural History and Classification. Cambridge, Mass. Dressler, R. L. 1993. Phylogeny and Classification of the Orchid Family. Portland. Homoya, M. A. 1993. Orchids of Indiana. Bloomington. Liggio, J. and A. Liggio. 1999. Wild Orchids of Texas. Austin. Luer, C. A. 1972. The Native Orchids of Florida. Bronx. Luer, C. A. 1975. The Native Orchids of the United States and Canada, Excluding Florida. Bronx. Magrath, L. K. 1973. The Native Orchids of the Prairies and Plains Region of North America. Ph.D. dissertation. University of Kansas. Morris, F. and E. A. Eames. 1929. Our Wild Orchids: Trails and Portraits. New York. Pridgeon, A. M., P. J. Cribb, and F. N. Rasmussen. 1999+. Genera Orchidacearum. 1+ vol. Oxford. Rasmussen, F. N. 1985. Orchids. In: R. M. T. Dahlgren et al. 1995. The Families of the Monocotyledons: Structure, Evolution, and Taxonomy. Berlin etc. Pp. 249–274. Sheehan, T. J. and M. Sheehan. 1994. An Illustrated Survey of Orchid Genera. Portland. Smith, W. R. 1993. Orchids of Minnesota. Minneapolis. Szlachetko, D. L. 1995. Systema orchidalium. Fragm. Florist. Geobot., suppl. 3. Whiting, R. E. and P. M. Catling. 1986. Orchids of Ontario: An Illustrated Guide. Ottawa. Williams, J. G. and A. E. Williams. 1983. Field Guide to Orchids of North America. New York.

Herbs or rarely vines, perennial, rarely annual, strongly mycotrophic, epiphytic, terrestrial, lithophytic, or rarely aquatic or subterranean, usually green and photosynthetic, some without chlorophyll and saprophytic. Roots subterranean or aerial, tuberoid or stolonoid, usually with spongy, multilayered velamen. Stems erect or pendent or modified into creeping rhizomes, simple or sympodially or monopodially branched, delicate to stout, or thickened as corms or pseudobulbs, or greatly reduced, sometimes proliferous (especially diverse in sympodial orchids). Leaves solitary, several, or reduced to scales, basal or cauline, alternate, distichous, or sometimes opposite or whorled, either convolute or duplicate, simple, sessile or petiolate; stipules absent; blade articulate or not, plicate or conduplicate, cylindric, triangular, or laterally flattened, margins entire. Inflorescences terminal or lateral, racemes, spikes, panicles, or rarely cymose, erect or variously pendent, 1–many-flowered, lax or dense, flowering successively or simultaneously. Flowers bisexual [rarely unisexual], epigynous, resupinate or not, pedicellate or sessile, 3-merous, usually bilaterally symmetric [rarely nearly radially symmetric], with abscission layer between pedicel and peduncle, rarely between ovary and perianth or ovary and pedicel; perianth of 6 tepals in 2 whorls, all petaloid or sepals sometimes greener and more foliaceous in texture; sepals alike or not, lateral sepals often connate (forming synsepal), or all 3 sepals variously connate and/or adnate or distinct and/or free; petals 3, median petal modified as lip, commonly larger or differing in form and color, lateral petals commonly but not always similar to sepals; nectaries of various sorts; extrafloral nectaries sometimes present on pedicels, bracts, or leaf sheaths; stamens usually 1–2(–3, if 3 the 3d modified into sterile staminode), all on side opposite lip, fully or partially adnate to style, forming column; pollen grains in monads or tetrads, usually in 2–8 pollinia, sometimes subdivided into small packets, rarely granular, sometimes pollinia with caudicles and/or stipes; gynoecium 3-carpellate, connate, forming compound, inferior, 1- or 3-locular ovary; style variously adnate to filaments; stigmas usually 3-lobed, concave to convex, part of median stigma lobe modified into rostellum, often separating anther from fertile portions of stigma, commonly preventing or in some cases facilitating self-pollination; ovules numerous, anatropous, minute. Fruits capsules, opening (dehiscing) by longitudinal slits, rarely fleshy and indehiscent berries. Seeds numerous (millions in some species), minute; endosperm absent.

Plantes herbacées terrestres ou épiphytes, sarmenteuses ou buisson-nantes, sympodiales et monopodiales, autotrophes ou occasionnellement saprophytes. Racines groupées à la base d'une tige ou dispersées le long d'une tige ou d'un rhizome, avec ou sans voile. Organes de réserve de formes variées. Feuilles soit pliées, soit convolutées ou dupliquées ou cylindriques, parfois squamiformes, caulinaires ou basales, sessiles ou pétiolées, articulées ou non. Inflorescence terminale ou axillaire, en épi, en racème ou en pani-cule, 1-n-flore. Fleurs de taille et de forme diverses, résupinées ou non. Tépale médian du cycle interne transformé en labelle le plus souvent distinct des autres. Ovaire l(-3)-loculaire. Gynostème: souvent pied basal de la colonne libre ou soudé avec le sommet de l'ovaire. Partie columnaire en général bien développée et formée par la soudure complète ou partielle des staminodes, du filet et du style, certains groupes exceptés. Stigmate humide, 3-2-1-lobé, souvent très modifié, concave à convexe, entier ou fendu en 2 parties. Lobe stigmatique médian transformé en un rostellum, structure de forme et de taille variées produisant une viscidie cellulaire ou parfois semi-fluide unique mais aussi double dans certains genres. La viscidie émet parfois une structure unciforme nommée hamulus. La tegula naît de la face abaxiale du rostellum. L'unique anthère fertile, qui correspond à l'étamine médiane du cycle externe, peut être dressée, réfléchie ou défléchie, fixée ou mobile ou même détachable. Connectif épais, charnu ou large, séparant ou recouvrant les deux loges. Pollinie en général compacte ou sectile, rarement granuleuse, formée de pollen en monades ou en tétrades; souvent en partie stérile, elle varie en forme et en taille. Les staminodes correspondent aux anthères latérales du cycle interne; rarement libres, ils sont digiti — ou aliformes et très souvent soudés à la colonne; leur sommet souvent libre varie par sa forme, sa taille et sa fonction. Fruit capsulaire, un peu charnu. Graines très fines, adaptées à l'ané-mochorie, exceptionnellement à la zoo- ou à l'hydrochorie.

Plantes'essentiellement herbacées, parfois un peu ligneuses, terrestres, lithophytes ou épiphytes, dressées ou rarement sarmenteuses à grimpantes, généralement autotrophes, quelquefois saprophytes ou hémiparasites; racines souterraines fasciculées, fibreuses ou charnues, parfois tubérisées; racines aériennes souvent chlorophylliennes et entourées d'un épiderme de cellules mortes (vélamen), opaque en atmosphère sèche et translucide en atmosphère humide; tiges souterraines souvent présentes, horizontales ou verticales, minces (rhizomes) ou épaissies (tubercules) et alors parfois bipartites et plurilobées; tiges aériennes minces ou épaissies et charnues à la base (pseudobulbes).'Feuilles'généralement présentes et développées, parfois nulles ou réduites, simples, radiculaires, basilaires à caulinaires, généralement engainantes, quelquefois à pétiole distinct; limbe membraneux, coriace ou charnu, plan ou plié longitudinalement avec parfois les deux moitiés soudées, à bord le plus souvent entier, exceptionnellement ondulé ou denticulé, à sommet acuminé, apiculé, aigu, obtus ou inégalement échancré.'Inflorescences'soit terminales sur une tige feuillée ou aphylle, soit latérales au pied d'une tige feuillée et stérile ou à l'aisselle de feuilles caulinaires, en racèmes, épis, capitules ou panicules, parfois uniflores; bractées présentes, développées ou réduites, quelquefois foliacées.'Fleurs'hermaphrodites, zygomorphes, à périanthe dichlamydé et trimère, homochlamydé ou hétérochlamydé mais à tépale médian du verticille externe parfois différent des latéraux (sépales) et à tépale médian (labelle) du verticille interne généralement de structure complexe et différente des latéraux (pétales); labelle soit inférieur (fleurs résupinées) par suite de la torsion dextrogyre de l'ovaire et éventuellement du pédicelle à 180 , soit supérieur (fleurs non résupinées) par suite de l'absence de torsion ou de la torsion dextrogyre de l'ovaire à 360 , simple ou divisé fondamentalement en 2 parties, l'hypochile, souvent en forme d'éperon, de sac ou de gouttière, et l'épichile, entier, crénelé, denté, échancré, lobé ou lacéré; androcée et gynécée (sauf l'ovaire) soudés en un ensemble appelé gynostème, face au labelle, parfois pédiculé, et souvent operculé, parfois surmonté de 2 appendices (stélidies); 1 seule étamine fertile (ontogéniquement la médiane du verticille interne), attachée par la base ( Basitonae ) ou par le sommet ( Acrotonae ), dressée, horizontale ou suspendue (parfois dans une logette appelée clinandre), à anthère biloculaire, introrse, composée de pollinies (agglomérats de tétrades de pollen), soit nombreuses, minuscules et granuleuses, soit par 2, 4, 8, plus grosses, ainsi que céracées ou cartilagineuses, souvent reliées entre elles par 2 axes filiformes (caudicules), à prolongement épaissi (stipe) et se terminant par 1 ou 2 glandes (viscidies), le tout formant un ensemble appelé parfois pollinarium; 2 staminodes latéraux quelquefois présents; ovaire infère, à 3 carpelles soudés, à placentation pariétale et uniloculaire; 3 stigmates, les latéraux fertiles, libres et souvent allongés ou soudés généralement en coupe, le médian le plus souvent transformé en appendice pollinisateur (rostelle) de forme variée.'Fruits': généralement capsules, à déhiscence longitudinale.'Graines nombreuses, microscopiques, anatropes, symbiotiques d'un champignon pour leur germination.\n\t\t\tCette famille est envisagée'sensu stricto . Elle est communément divisée en 3 sous-familles :'Apostasioideae ,'Cypripedioideae ,'Orchidioideae , considérées comme des familles distinctes par l'auteur. Les'Apostasiaceae'(avec 2 genres) sont caractérisées par un labelle peu distinct et par 3 étamines fertiles. Les'Cypripediaceae'(avec 4 genres) sont caractérisées par un labelle sacciforme, par les 2 étamines latérales fertiles et par la médiane transformée en staminode. Ces familles ne sont pas représentées en Afrique et forment avec les'Orchidaceae , l'ordre des'Orchidales. \n\t\t\tFamille cosmopolite mais surtout tropicale, comprenant plus de 700 genres, 20.000 espèces et 200.000 cultivars. Pour la flore : 65 genres et près de 500 espèces.\n\t\t\tL'ordre des genres traités ici suit la classification de Dressler (The Orchids, Natural Histology and Classification, Ed. Smithsonian Institution, Washington, 332 pp., 1981).\n\t\t\tLes caractères du gynostème sont essentiels pour la délimitation des genres; cependant, ils ne sont guère aisés à utiliser par les profanes et c'est pourquoi ils sont peu mentionnés dans la clé afin de la rendre la plus pratique possible.\n\t\t\tDans certaines villes d'Afrique centrale,'Epidendrum ybaguense'Kunth (syn. :'E. radicans'Pavon ex Lindley) est utilisé comme plante ornementale pour la décoration des avenues, et'Vanilla planifolia'Andrews (syn. :'V. fragrans Ames) est cultivé pour ses fruits aromatiques.\n\t\t\tPlusieurs ouvrages consacrés aux Orchidées d'Afrique et illustrés de photographies, d'aquarelles ou de dessins, ont paru ces dernières années et peuvent aider à leur identification :\n\t\t\tBall. J. S., Southern African Epiphytic Orchids, ed. Conservation Press, Johannesburg, 247 pp., 24 photos, 104 pl., 104 cartes (1978).\n\t\t\tMorris В., Epiphytic Orchids of Malawi, ed. Society of Malawi, Blantyre, 136 pp., 4 pl. + 1 frontispice, 25 fig. (1970).\n\t\t\tPiers F., Orchids of East Africa, ed. 2, Cramer, Lehre, 304 pp., 116 fig. (1968).\n\t\t\tSchelpe E.A., An Introduction to the South African Orchids, ed. Macdonald, London, 109 pp., 64 pl., 47 fig. (1968).\n\t\t\tSegerbäck L.B. , Orchids of Nigeria, ed. Balkema, Rotterdam, 111 pp., 5 pl., 149 fig. (1983).\n\t\t\tStewart J. & Campbell В., Orchids of Tropical Africa, ed. Allen, London, 117 pp., 45 pl. (1970).\n\t\t\tStewart J. & Hennessey E.F., Orchids of Africa, ed. Macmillan, London, 159 pp., 50 pl., 8 fig. (1981).\n\t\t\tStewart J., Linder H. R., Schelpe E. A. & Hall A. V., Wild Orchids of Southern Africa, ed. Macmillan, Johannesburg, 307 pp., 400 photos (1982).\n\t\t\tWilliamson G., Orchids of South Central Africa, ed. Dent & Sons, London, 237 pp., 185 photos, 120 fig. (1977).

Leaves undivided, alternate and often distichous, rarely opposite, sometimes all reduced to scales, often fleshy, sheathing at the base Seeds very numerous, minute, often drawn out at each end, or rarely winged, without endosperm; embryo not differentiated Ovules very numerous and minute Fruit usually a capsule, mostly opening laterally by 3 or 6 longitudinal slits Stamens 2 or 1; stamens and style united to form a special structure (column), the apex of which may be produced vertically into stelidia or laterally into wings, and the base of which may be produced downwards to form a foot; anther or anthers 2-locular, introrse, opening by a slit lengthwise; often operculate, i$e$ can be lifted like a little cap; pollen granular or generally agglutinated into mealy, waxy or bony masses (pollinia); at one end the pollinium may be extended into a sterile portion (caudicle); the pollinia may be free in the anther-loculi or more or less loosely united Ovary inferior, 1-locular with 3 parietal placentas or very rarely 3-locular with axile placentas, usually produced at the apex to form the column; stigmas 3 fertile, or more frequently the lateral 2 fertile, the other sterile and transformed into a small outgrowth (rostellum) which lies between the anther and the stigmas; a portion of the rostellum is sometimes modified into a viscid disk or disks (viscidia) to which the pollinia are attached, often by a stalk or stipes Flowers bracteate, hermaphrodite or very rarely polygamous or monoecious, zygomorphic; inflorescence spicate, racemose or paniculate, or flowers solitary Perianth epigynous, composed of 6 petaloid segments (tepals) in 2 whorls, or the outer whorl calyx-like and the inner corolla-like, or the outer rarely corolla-like and the inner minute, free or variously connate in each whorl; outer segments (sepals) imbricate or subvalvate, the middle segments of each whorl generally different in size and colour from the lateral ones, especially the middle petal which is often extremely complicated in structure and is termed the lip or labellum; the basal part of the labellum, the hypochile, is often articulated to the base of the column or is much constricted, when it is termed the claw; the middle part, the mesochile and the apical part, the epichile, may be variously lobed and often bear outgrowths. On account of the twisting of the ovary through 180°, the labellum is often placed in an abaxial position; frequently the labellum or more rarely the odd sepal is prolonged into a sac or spur, sometimes very long Perennial, terrestrial, epiphytic or saprophytic herbs with rhizomes or tuberous roots or rootstock; stem leafy or scapose, frequently thickened at the base into pseudobulbs and bearing aerial assimilating roots Seeds very numerous, minute, often drawn out at each end, or rarely winged, without endosperm; embryo not differentiated Ovules very numerous and minute Fruit usually a capsule, mostly opening laterally by 3 or 6 longitudinal slits Stamens 2 or 1; stamens and style united to form a special structure (column), the apex of which may be produced vertically into stelidia or laterally into wings, and the base of which may be produced downwards to form a foot; anther or anthers 2-locular, introrse, opening by a slit lengthwise; often operculate, i$e$ can be lifted like a little cap; pollen granular or generally agglutinated into mealy, waxy or bony masses (pollinia); at one end the pollinium may be extended into a sterile portion (caudicle); the pollinia may be free in the anther-loculi or more or less loosely united Ovary inferior, 1-locular with 3 parietal placentas or very rarely 3-locular with axile placentas, usually produced at the apex to form the column; stigmas 3 fertile, or more frequently the lateral 2 fertile, the other sterile and transformed into a small outgrowth (rostellum) which lies between the anther and the stigmas; a portion of the rostellum is sometimes modified into a viscid disk or disks (viscidia) to which the pollinia are attached, often by a stalk or stipes Flowers bracteate, hermaphrodite or very rarely polygamous or monoecious, zygomorphic; inflorescence spicate, racemose or paniculate, or flowers solitary Perianth epigynous, composed of 6 petaloid segments (tepals) in 2 whorls, or the outer whorl calyx-like and the inner corolla-like, or the outer rarely corolla-like and the inner minute, free or variously connate in each whorl; outer segments (sepals) imbricate or subvalvate, the middle segments of each whorl generally different in size and colour from the lateral ones, especially the middle petal which is often extremely complicated in structure and is termed the lip or labellum; the basal part of the labellum, the hypochile, is often articulated to the base of the column or is much constricted, when it is termed the claw; the middle part, the mesochile and the apical part, the epichile, may be variously lobed and often bear outgrowths. On account of the twisting of the ovary through 180°, the labellum is often placed in an abaxial position; frequently the labellum or more rarely the odd sepal is prolonged into a sac or spur, sometimes very long Perennial, terrestrial, epiphytic or saprophytic herbs with rhizomes or tuberous roots or rootstock; stem leafy or scapose, frequently thickened at the base into pseudobulbs and bearing aerial assimilating roots

Leaves glabrous or occasionally hairy, entire except at the apex in some cases, alternate or occasionally opposite, often distichous, frequently fleshy and often terete or canaliculate, almost always with a basal sheath which frequently sheaths the stem, sometimes articulated at the base of the lamina and sometimes with a false petiole Stems usually leafy, but leaves often reduced to bract-like scales, one or more internodes at the base often swollen to form a pseudobulb; aerial, assimilating adventitious roots, often bearing one or more layers of dead cells called a velamen, are borne in epiphytic species Flowers small to large, often quite showy, hermaphrodite or rarely monoecious and polymorphic, sessile or variously pedicellate, most often twisted through 180 degrees, occasionally not twisted or twisted through 360 degrees Inflorescences erect to pendent, spicate, racemose or paniculate, one to many-flowered, basal, lateral or terminal, the flowers rarely secund or distichously arranged Growth either sympodial or less commonly monopodial Perennial, terrestrial, saprophytic or epiphytic herbs or rarely scrambling climbers, with rhizomes, root-stem tuberoids or rootstocks with mycorrhizal fungi in the roots and often elsewhere Ovary inferior, unilocular and the placentation parietal, or rarely trilocular and the placentation axile Perianth epigynous, of two whorls of three segments; outer perianth whorl (sepals) usually free but sometimes variously adnate, the median (dorsal) often dissimilar to the laterals, the laterals sometimes adnate to the column foot to form a saccate, conical or spur-like mentum; inner whorl comprising two lateral petals and a median lip; petals free or rarely partly adnate to sepals, similar to sepals or not, often showy; lip entire, variously lobed or two or three-partite, ornamented or not with calli, ridges, hair cushions or crests, with or without a basal spur or nectary, margins entire to laciniate Stylar and filamentous tissue forming a long or short column, with or without a basal foot, occasionally winged or with lobes or arms at apex or ventrally; anther one (or rarely two or three in extra African taxa), terminal or ventral on column, with a concave anther cap or opening by longitudinal slits; pollen in tetrads, agglutinated into discrete masses called pollinia; pollinia mealy, waxy or horny, sectile or not, 2, 4, 6 or 8, sessile or attached by caudicles, a stipes or stipites to one or two sticky viscidia; stigma 3-lobed, the mid-lobe often modified to form a rostellum, the other lobes either sunken on the ventral surface of the column behind the anther or with two lobes porrect Fruit a capsule, opening laterally by 3 or 6 slits; seeds numerous, dust-like, lacking endosperm, sometimes markedly winged Stems usually leafy, but leaves often reduced to bract-like scales, one or more internodes at the base often swollen to form a pseudobulb; aerial, assimilating adventitious roots, often bearing one or more layers of dead cells called a velamen, are borne in epiphytic species Flowers small to large, often quite showy, hermaphrodite or rarely monoecious and polymorphic, sessile or variously pedicellate, most often twisted through 180 degrees, occasionally not twisted or twisted through 360 degrees Inflorescences erect to pendent, spicate, racemose or paniculate, one to many-flowered, basal, lateral or terminal, the flowers rarely secund or distichously arranged Growth either sympodial or less commonly monopodial Perennial, terrestrial, saprophytic or epiphytic herbs or rarely scrambling climbers, with rhizomes, root-stem tuberoids or rootstocks with mycorrhizal fungi in the roots and often elsewhere Ovary inferior, unilocular and the placentation parietal, or rarely trilocular and the placentation axile Perianth epigynous, of two whorls of three segments; outer perianth whorl (sepals) usually free but sometimes variously adnate, the median (dorsal) often dissimilar to the laterals, the laterals sometimes adnate to the column foot to form a saccate, conical or spur-like mentum; inner whorl comprising two lateral petals and a median lip; petals free or rarely partly adnate to sepals, similar to sepals or not, often showy; lip entire, variously lobed or two or three-partite, ornamented or not with calli, ridges, hair cushions or crests, with or without a basal spur or nectary, margins entire to laciniate Stylar and filamentous tissue forming a long or short column, with or without a basal foot, occasionally winged or with lobes or arms at apex or ventrally; anther one (or rarely two or three in extra African taxa), terminal or ventral on column, with a concave anther cap or opening by longitudinal slits; pollen in tetrads, agglutinated into discrete masses called pollinia; pollinia mealy, waxy or horny, sectile or not, 2, 4, 6 or 8, sessile or attached by caudicles, a stipes or stipites to one or two sticky viscidia; stigma 3-lobed, the mid-lobe often modified to form a rostellum, the other lobes either sunken on the ventral surface of the column behind the anther or with two lobes porrect Fruit a capsule, opening laterally by 3 or 6 slits; seeds numerous, dust-like, lacking endosperm, sometimes markedly winged

Fls perfect, irregular, usually resupinate (twisted in ontogeny so that the morphologically adaxial side appears to be abaxial); sep 3 (or 2 by fusion), green or colored, often resembling the lateral pet; pet 3, usually colored or white, the 2 lateral ones consimilar and evidently different from the third (typically the lowest) one, called the lip; stamen typically one, adnate to the style on the opposite side from the lip, forming a usually stout stylar column with the bilocular anther terminal or subterminal and separated from the proper stigmatic surface by an enlarged rostellum derived from the adjacent stigma-lobe, the 2 functional stigma-lobes often connate (in Cypripedium 2 anthers and an expanded staminode borne on the column, which lacks a rostellum); pollen monadinous and only loosely coherent in Cypripedium, in our other genera tetradinous and organized into 1–6 pollinia in each locule of the anther; one end of a pollinium often prolonged into a slender tip attached to a sticky pad, the viscidium (a detachable portion of the rostellum), the viscidium and its attached pollinium or pollinia collectively forming a pollinarium; ovary inferior, unilocular, with very numerous, late-developing ovules on 3 expanded parietal placentas; fr mostly capsular, opening by 3(6) longitudinal slits but remaining closed top and bottom; seeds countless, minute; embryo mostly undifferentiated, only seldom with a barely recognizable cotyledon; endosperm wanting; strongly mycotrophic (sometimes nongreen) perennial herbs (many of the tropical ones epiphytic) with alternate (seldom opposite or whorled), parallel-veined, often somewhat fleshy lvs sheathing at base, the fls solitary or more often in racemes, spikes, or panicles; generally individually subtended by a bract. 600/15,000+.

Perennial, but sometimes short-lived, terrestrial, epiphytic, or lithophytic, autotrophic or rarely mycotrophic herbs (or rarely scrambling vines), with rhizomes, tubers, or rootstocks with mycorrhizal fungi in roots. Stems either sympodial or monopodial, usually leafy, but leaves sometimes reduced to bractlike scales, 1 or more internodes at base often swollen to form a "pseudobulb"; epiphytic species with aerial, photosynthesizing adventitious roots, often bearing 1 or more layers of dead cells (velamen). Leaves 1 to many, alternate or occasionally opposite, often distichous, sometimes terete or canaliculate, glabrous or very rarely hairy, frequently fleshy or leathery, base almost always sheathing, sometimes articulated, sometimes forming a false petiole, margin entire, apex often emarginate. Inflorescence basal, lateral, or terminal, erect to pendulous, racemose, spicate, subumbellate, or paniculate, 1- to many flowered, flowers rarely secund or distichously arranged. Flowers small to large, often quite showy, usually zygomorphic, very rarely ± actinomorphic, bisexual [very rarely monoecious and polymorphic], sessile or pedicellate, most often resupinate with pedicel and ovary twisted through 180°, occasionally not twisted or twisted through 360°. Ovary inferior, 1-locular, placentation parietal (or rarely 3-locular and placentation axile). Sepals usually free but sometimes variously adnate, median (dorsal) one often dissimilar to laterals, laterals sometimes adnate to a column foot to form a saccate, conic, or spurlike mentum. Petals free or rarely partly adnate to sepals, similar to sepals or not, often showy; lip entire, variously lobed or 2- or 3-partite, ornamented or not with calli, ridges, hair cushions, or crests, with or without a basal spur or nectary, margins entire to laciniate. Column short to long, with or without a basal foot, occasionally winged or with lobes or arms at apex or ventrally; anther mostly 1, less often 2 or 3, terminal or ventral on column, caplike or opening by longitudinal slits; pollen usually forming distinct pollinia, less often loose, pollinia 2, 4, 6, or 8, mealy, waxy, or horny, sectile or not, sessile or attached by stalks (caudicles or stipes) to 1 or 2 sticky viscidia; stigma 3-lobed, mid-lobe often modified to form a rostellum, other lobes either sunken on ventral surface of column behind anther or with 2 lobes porrect. Fruit a capsule, rarely berrylike, usually opening laterally by 3 or 6 slits. Seeds very numerous, dustlike, lacking endosperm, rarely winged.

Anthers attached by their bases or apices, opening by a slit lengthwise or often operculate; pollen in distinct tetrads, sticky or agglutinated into 2, 4, 6 or 8 pollinia; pollinia mealy, waxy or horny masses, often divided into a number of smaller portions (sectile); at one end each pollinium occasionally drawn out into a sterile caudicle Ovary inferior, 1-locular with 3 parietal placentas or rarely 3-locular with axile placentation, produced at the apex to form the column; very rarely apex of ovary with ring-like outgrowth (calyculus); ovules very small and numerous Stamens 1, 2 or 3, ± united with the style to form a special organ termed the column (gynostegium), apical part of which may be produced laterally into wings or vertically into stelidia, basal part often produced downwards to form a column-foot Mentum or chin frequently formed from lateral sepals where tepals join column-foot Fruit a capsule opening laterally by 3 or 6 longitudinal slits Seeds very numerous and small, without endosperm and with an undifferentiated embryo, often markedly winged Stigmas 3, fertile or more usually the 2 lateral ones fertile and the other transformed into an outgrowth (rostellum) lying between the anther and the lateral stigmas; part of the rostellum often modified into a sticky disk or disks called viscidia to which the pollinia are attached by 1 or 2 stalks (stipes) also derived from rostellum or by the sterile caudicle The whole structure of pollinia, stipes or caudicle and viscidium form the pollinarium The segments of the outer whorl and 2 lateral segments of the inner whorl termed tepals, especially when basically similar in size, shape and colour Median segment of inner whorl almost always markedly different from the 2 lateral segments Flowers bracteate, hermaphrodite or very rarely polygamous or monoecious, zygomorphic, sessile or variously pedicellate, most often twisted through 180° (resupinate), occasionally not twisted or twisted through 360° Inflorescence spicate, racemose or paniculate, terminal and/or axillary, the flowers rarely secundly or distichously arranged, or flowers solitary Median segment of outer whorl (“dorsal” sepal) often different in size and shape from the 2 laterals, sometimes saccate or with 1 or 2 spurs Perianth epigynous; perianth-segments 6, usually free but less frequently variously adnate, connate or adherent to one another or to the column, arranged in 2 whorls; both whorls similar or outer whorl (sepals) calyx-like and inner (petals) corolla-like, or outer whorl corolla-like and inner very reduced Growth usually sympodial, occasionally monopodial Perennial, terrestrial, saprophytic, epiphytic or very rarely subterranean or aquatic herbs or rarely scramblers, with rhizomes, tubers or rootstocks with mycorrhizal fungi in the roots and usually elsewhere Leaves rarely hairy, undivided except at apex in some cases, alternate or very occasionally opposite, often distichous, frequently fleshy and often terete or canaliculate, almost always with a basal sheath which frequently surrounds the base of the peduncle, sometimes articulated at base of lamina and sometimes with a false petiole Stems usually leafy, but leaves often reduced to bract-like sheathing scales, one or more internodes at or near the base frequently variously swollen into a “pseudobulb”; those of epiphytic species often bearing aerial assimilating roots protected from excessive heat and water-loss by layers of dead cells called the velamen Median segment of inner whorl (lip or labellum) entire or variously lobed, frequently laciniate or fimbriate, often brightly coloured and frequently spotted or otherwise ornamented, often bearing crests (keels or carinae) along its length or with central portion (disk) or throat bearing a callus or cushion of hairs, often produced backwards into a sac or spur (rarely 2) up to 30 cm. long and sometimes with nectar at apex; often differentiated into 2 or 3 parts: basal part termed hypochile, often hinged to base of column or narrowed into a claw; middle part termed mesochile; apical part termed epichile Ovary inferior, 1-locular with 3 parietal placentas or rarely 3-locular with axile placentation, produced at the apex to form the column; very rarely apex of ovary with ring-like outgrowth (calyculus); ovules very small and numerous Stamens 1, 2 or 3, ± united with the style to form a special organ termed the column (gynostegium), apical part of which may be produced laterally into wings or vertically into stelidia, basal part often produced downwards to form a column-foot Mentum or chin frequently formed from lateral sepals where tepals join column-foot Fruit a capsule opening laterally by 3 or 6 longitudinal slits Seeds very numerous and small, without endosperm and with an undifferentiated embryo, often markedly winged Stigmas 3, fertile or more usually the 2 lateral ones fertile and the other transformed into an outgrowth (rostellum) lying between the anther and the lateral stigmas; part of the rostellum often modified into a sticky disk or disks called viscidia to which the pollinia are attached by 1 or 2 stalks (stipes) also derived from rostellum or by the sterile caudicle The whole structure of pollinia, stipes or caudicle and viscidium form the pollinarium The segments of the outer whorl and 2 lateral segments of the inner whorl termed tepals, especially when basically similar in size, shape and colour Median segment of inner whorl almost always markedly different from the 2 lateral segments Flowers bracteate, hermaphrodite or very rarely polygamous or monoecious, zygomorphic, sessile or variously pedicellate, most often twisted through 180° (resupinate), occasionally not twisted or twisted through 360° Inflorescence spicate, racemose or paniculate, terminal and/or axillary, the flowers rarely secundly or distichously arranged, or flowers solitary Median segment of outer whorl (“dorsal” sepal) often different in size and shape from the 2 laterals, sometimes saccate or with 1 or 2 spurs Perianth epigynous; perianth-segments 6, usually free but less frequently variously adnate, connate or adherent to one another or to the column, arranged in 2 whorls; both whorls similar or outer whorl (sepals) calyx-like and inner (petals) corolla-like, or outer whorl corolla-like and inner very reduced Growth usually sympodial, occasionally monopodial Perennial, terrestrial, saprophytic, epiphytic or very rarely subterranean or aquatic herbs or rarely scramblers, with rhizomes, tubers or rootstocks with mycorrhizal fungi in the roots and usually elsewhere Leaves rarely hairy, undivided except at apex in some cases, alternate or very occasionally opposite, often distichous, frequently fleshy and often terete or canaliculate, almost always with a basal sheath which frequently surrounds the base of the peduncle, sometimes articulated at base of lamina and sometimes with a false petiole Stems usually leafy, but leaves often reduced to bract-like sheathing scales, one or more internodes at or near the base frequently variously swollen into a “pseudobulb”; those of epiphytic species often bearing aerial assimilating roots protected from excessive heat and water-loss by layers of dead cells called the velamen Median segment of inner whorl (lip or labellum) entire or variously lobed, frequently laciniate or fimbriate, often brightly coloured and frequently spotted or otherwise ornamented, often bearing crests (keels or carinae) along its length or with central portion (disk) or throat bearing a callus or cushion of hairs, often produced backwards into a sac or spur (rarely 2) up to 30 cm. long and sometimes with nectar at apex; often differentiated into 2 or 3 parts: basal part termed hypochile, often hinged to base of column or narrowed into a claw; middle part termed mesochile; apical part termed epichile