ORCHIDACEAE
NB A very large family with many genera in the region. The family is divided in fice subfamilies: Apostasioideae, VAnilloideae, Cyprepidioideae, Epidendroideae, Orchidoideae). Not all genera are taken up in this online key. See also in Linnaeus: Orchids of the Philippines and Orchids of New Guinea
Morphological description
Sympodial or monopodial herbs. Usually epiphytes, leaves leathery, stems green, very fleshy or bulbously swollen (pseudobulbs), roots with a layer of water-absorbing dead cells, often white when dry (velamen). Sometimes: Climbing stems (s), or very long climbing rhizomes (r): Arachnis (s) pp, Bulbophyllum (r) pp, Claderia (r), Coelogyne (r) pp, Dendrobium (s) pp, Dipodium (s) pp, Epigeneium (r) pp, Eria (r) pp, Erythrorchis (s), Galeola (s), Glomera (s) pp, Mediocalcar (r) pp, Micropera (s) pp, Pseuderia (s), Pseudovanilla (s), Renanthera (s) pp, Vanilla (s).
Leaves
Leaves simple, usually leathery. Sometimes: Leaves laterally flattened: Bromheadia, Ceratochilus, Dendrobium pp, Eria pp, Hippeophyllum, Jejewoodia, Microsaccus, Oberonia, Octarrhena, Phreatia pp, Podochilus pp. - Leaves terete: Bulbophyllum pp, Ceratostylis pp, Cleisocentron pp, Cleisostoma pp, Cordiglottis, Dendrobium pp, Dendrochilum pp, Eria pp, Glomera pp, Luisia, Microtis, Octarrhena pp, Papilionanthe, Paraphalaenopsis, Phragmorchis, Rhynchogyna, Schoenorchis pp, Thrixspermum pp. - Leaves or leaf-sheaths conspicuously hairy: Calanthe pp, Dendrobium pp, Glomera pp, Nervilia pp, Pilophyllum, Plocoglottis pp, Trichotosia. - Leaves with silvery, pink, or golden veins (•Jewel orchids°o): Anoectochilus pp, Corybas pp, Dossinia, Goodyera pp, Ludisia, Macodes, Myrmechis pp, Papuaea, Rhomboda, Vrydagzynea pp. - Leafless terrestrials without chlorophyll (•saprophytes°o, in fact parasites on fungi): Aphyllorchis, Corybas pp, Cyrtosia, Cystorchis pp, Didymoplexiella, Didymoplexis, Dipodium pp, Epipogium, Erythrorchis, Eulophia pp, Galeola, Gastrodia, Lecanorchis, Neoclemensia, Platanthera pp, Pseudovanilla, Silvorchis, Stereosandra, Tropidia pp. - Leafless epiphytes: Chiloschista, Microtatorchis pp, Taeniophyllum.
Inflorescence
Inflorescence.
Flowers
Flower perfect, zygomorphic, 3-merous (seemingly 5-merous in some genera with connate lateral sepals: Acriopsis, Paphiopedilum); stamen adnate to the pistil, forming a compound structure (column); pollen coherent in small waxy or granular bodies of definite shape and size (pollinia), rarely gel- or powder-like; ovary inferior. Usually flowers resupinate, median petal (lip) very different (in shape, size, and /or coloration) from the lateral petals; fertile stamen(s) 1, rarely 2 or 3. Sometimes: Large, showy flowers: Acanthephippium, Amesiella, Arachnis, Armodorum, Arundina, Bromheadia pp, Bulbophyllum pp, Calanthe pp, Chelonistele pp, Coelogyne pp, Cymbidium pp, Dendrobium pp, Dilochia pp, Dimorphorchis, Diplocaulobium pp, Dipodium pp, Epigeneium pp, Grammatophyllum, Gynoglottis pp, Paphiopedilum, Papilionanthe, Paraphalaenopsis, Pecteilis, Phaius pp, Phalaenopsis pp, Pteroceras pp, Renanthera pp, Rhynchostylis, Spathoglottis, Tainia pp, Thrixspermum pp, Thunia, Trichoglottis pp, Vanda, Vandopsis, Vanilla pp. - Sepals connate: Acanthephippium, Acriopsis, Appendicula, Bracisepalum, Bulbophyllum pp, Cadetia pp, Ceratostylis pp, Cheirostylis, Corybas pp, Dendrobium pp, Didymoplexiella, Didymoplexis, Gastrodia, Glomera, Mediocalcar, Microtatorchis, Myrmechis pp, Neoclemensia, Octarrhena pp, Paphiopedilum, Podochilus, Porpax, Pristiglottis pp, Pterostylis, Taeniophyllum pp, Tropidia pp, Vexillabium. Sometimes dimorphic flowers: Bulbophyllum mirabile, Dimorphorchis, Grammatophyllum pp.
Fruit
Fruit a dry capsule splitting lengthways, with dust-like seed.
Seed
Seeds numerous, minute, lacking endosperm.
Different from: Amaryllidaceae: orchids never possess tunicate bulbs, never have more than 3 anthers, filament of anthers in orchids always adnate to the pistil (rarely so in Amaryllidaceae), orchid flowers are never truly actinomorphic, orchid seeds lack endosperm. - Burmanniaceae: orchid flowers are never completely sympetalous: at least the lip is free from the petals; orchid inflorescences are not bifurcate. - Corsiaceae: orchids never have 6 stamens. - Hypoxidaceae: orchids never have 6 stamens and truly actinomorphic flowers; no tristichous phyllotaxy in orchids; orchid seeds lack endosperm. - Zingiberaceae: orchid plants are not aromatic; in Zingiberaceae the lip is formed by two connate sterile stamens, not by the median corolla lobe as in orchids; in Zingiberaceae there is in addition to the lip a 3-lobed corolla and a tubular, usually 3-lobed calyx; orchid seeds lack endosperm..
Distribution: The family is cosmopolitan. In Malesia about 210 genera, including: - Agrostophyllum (Asia, Indo-Malesia, Pacific), epiphytes, inflorescences very short in dense terminal clusters, leaf-sheaths with blackish margins; - Apostasia (Asia, Indo-Malesia, Pacific), terrestrials, 2 fertile anthers, lip similar to petals; - Appendicula (Asia, Indo-Australia, Pacific), epiphytes, small flowers, 6 pollinia; - Arundina (Asia, Malesia) terrestrial, reed-like stems, Cattleya-like flowers appearing in succession; - Bromheadia (Asia, Indo-Australia), terrestrials and epiphytes, inflorescences terminal, with dense distichous bracts, flowers successive, ephemeral; - Bulbophyllum (pantropical), epiphytes, 1- or rarely 2-leaved pseudobulbs, basal inflorescences, mainly fly-pollination syndrome, largest genus in Malesia (> 800 species); - Calanthe (pantropical), terrestrials, spurred flowers, lip adnate to column, all parts becoming bluish when bruised; - Ceratostylis (Asia, Indo-Malesia, Pacific), epiphytes, often rush-like habit; - Cleisostoma (Asia, Indo-Australia, Pacific), epiphytes, monopodial, small spurred flowers, the spur almost blocked by an internal callus; - Coelogyne (Asia, Indo-Malesia, Pacific), epiphytes, showy flowers, lip with erect side-lobes, flattened column; - Corybas (Asia, Indo-Australia, Pacific), terrestrials, dwarf plants with one cordate leaf and one helmet-shaped flower; - Cymbidium (Asia, Indo-Australia), epiphytes, pseudobulbs or stems with few to several sheathing leaves, lip with erect side-lobes; - Dendrobium (Asia, Indo-Australia, Pacific), epiphytes, extremely diverse genus, inflorescences arising from upper half of the stem, pollinia 4, oblong, in two pairs, second largest genus in Malesia (> 700 species); - Dendrochilum (Indo-Malesia), epiphytes, 1-leaved pseudobulbs, racemes of small flowers which are arranged in two ranks; - Dipodium (Asia, Indo-Australia, Pacific), terrestrials, leaves distichous, strapshaped, stem often climbing, sometimes plant leafless and not scandent; fairly large spotted flowers; - Epigeneium (Asia, West Malesia), epiphytes, long rhizomes, 1- or 2-leaved pseudobulbs, terminal, few-flowered inflorescences, pollinia as in Dendrobium; - Eria (Asia, Indo-Australia, Pacific), epiphytes, roots often thin, brown, and hairy, flowers with distinct column-foot, pollinia 8; - Flickingeria (Asia, Indo-Malesia, Pacific), epiphytes with erect, branching rhizomes, short, 1-flowered inflorescences, pollinia as in Dendrobium; - Galeola (Indo-Malesia), lianas, lacking leaves and chlorophyll; - Gastrodia (Asia, Indo-Australia, Pacific), terrestrials, lacking leaves and chlorophyll, sepals and petals connate; - Glomera (Malesia, Pacific), epiphytes or terrestrials, inflorescence a head-like terminal raceme, apex of lip often red or black; - Goodyera (circumboreal, Asia, Indo-Australia, Pacific), terrestrials, fleshy rhizome, lip papillose-hairy inside at the base; - Grammatophyllum (Indo-Malesia), epiphytes, large to enormous pseudobulbs, big spotted flowers; - Habenaria (Pantropical), terrestrial, flowers white or green, lip spurred, pollinia 2; - Liparis (cosmopolitan), epiphytes or terrestrials, terminal racemes of small flowers, lip geniculate; - Macodes (Malesia), mainly terrestrial, leaves with silvery or golden reticulate veins, flowers strongly asymmetric; - Malaxis (cosmopolitan), mainly terrestrial, racemes with small, not resupinate flowers; - Nervilia (Africa, Asia, Indo-Pacific), terrestrial, leaves round, plicate, inflorescences appearing before the leaves; - Oberonia (Africa, Asia, Indo-Pacific), epiphytes, leaves laterally flattened, terminal inflorescences with many minute flowers; - Paphiopedilum (Asia, Malesia), terrestrial or sometimes epiphytic, flowers large, lip slipper-shaped; - Phalaenopsis (Asia, Malesia, Australia), epiphytes, short monopodial stem, broad leaves, showy flowers; - Spathoglottis (Asia, Indo-Pacific), terrestrial, raceme with showy flowers, lip with bilobed callus; - Taeniophyllum (Africa, Asia, Indo-Pacific), epiphytes, leafless, spurred flowers; - Thrixspermum (Asia, Indo-Pacific), epiphytes, monopodial, often with prominent distichous bracts; - Trichotosia (Asia, Malesia), mostly epiphytes; leaves usually covered with redbrown or yellow hairs; - Vanda (Asia, Indo-Australia), epiphytes; monopodial, strap-shaped leaves, large showy flowers; - Vanilla (Pantropical), lianas, leaves not sheathing, stem green, with a root at each node.
Notes: This is the largest family in Malesia, with 4300- 4900 species. Most are restricted to primary forests, where they may be found from the lowlands up to the timber line, but predominantly in the montane zone (1000-2000 m). The great majority are epiphytes. Individual species tend to be widely distributed, but often occur only sporadically within their area. Many orchids possess highly specialised pollination mechanisms, but our knowledge about the Malesian taxa is extremely scanty. Most of the ornamental species have become scarce due to indiscriminate collecting, especially members of genera like Paphiopedilum, Phalaenopsis, and Vanda. The main threat to the family as a whole, however, is undoubtedly the destruction of the primary forests. - Very few of the Malesian taxa can be considered useful to man except as ornamentals (beauty is not generally considered a useful property); in the Moluccas and New Guinea species of Diplocaulobium and Dendrobium furnish a tough yellow fibre, made from strips of the stems, which are widely applied in weaving carrying bags, belts, head bands, etc. Some orchids reputedly possess medicinal or magical properties. The dried fruits of Vanilla planifolia are widely used for flavouring cakes and other sweets
Literature: R.L. Dressler, The Orchids. Natural history and classification (1981); R. Schlechter, The Orchidaceae of German New Guinea (1982); J.B. Comber, Orchids of Java (1990); G. Seidenfaden & J. J. Wood, The Orchids of Peninsular Malaysia and Singapore (1992).
Spot characters (Van Balgooy): Orchidaceae 81, 92 - Aphyllorchis 7 - Bromheadia 23 - Calanthe 54 - Chiloschista 8 - Corybas 7 - Cyrtosia 7 - Cystorchis 7 - Dendrobium 24 - Didymoplexiella 7 - Didymoplexis 7 - Dipodium scandens 5 - Epipogium 7 - Erythrorchis 7 - Eulophia 7 - Galeola 5 - Gastrodia 7 - Lecanorchis 7 - Micropera 5 - Microtatorchis 8 - Neoclemensia 7 - Platanthera 7 - Pseuderia 5 - Pseudovanilla 5, 7 - Renanthera 5 - Silvorchis 7 - Stereosandra 7 - Taeniophyllum 8 - Tropidia 7 - Vanilla 5.
Illustrations: Fig. 127. Aerides odorata Lour. (Orchidaceae). Reproduced from J. Veitch, A manual of Orchidaceous plants (1891) fig. 7, opposite p. 81. Fig. 128. Apostasia odorata Blume (Orchidaceae). Habit; enlarged flower. Reproduced from Blumea 17 (1969) 342, fig. 12a, b. 163 (Orchidaceae continued) Fig. 129. Bulbophyllum callichroma Schltr. (Orchidaceae). Reproduced from Orchid Monographs 7 (1993) 228, fig. 51a. 165 (Orchidaceae continued) 166 Fig. 130. Cystorchis aphylla Ridl. (left) and Epipogium roseum (D. Don) Lindl. (right) (Orchidaceae). Reproduced from H. Burgeff, Saprophytismus und Symbiose (1932). (Orchidaceae continued), Fig. 131. Mischobulbum papuanum (J. J. Sm.) Schltr. (Orchidaceae). Reproduced from Orchid Monographs 6 (1992) 144, fig. 39a. Schuiteman, Fig. 132. Taeniophylum radiatum J. J. Sm. (Orchidaceae). Habit; enlarged inflorescence (drawing by J.J. Smith & Darmosoediro). Reproduced from Bull. Jard. Bot. Buitenzorg III, 6 (1924) t. 21 II a, b. 169 Fl. Males. Bull. 12 (1999) 273-287)-
Image in PhytoImages for Orchidaceae