Polystachya Hook.
  • Hook., Exot. Fl. 2: t. 103 (1824)


This is a synonym of Polystachyinae Schltr.

General Description

{i}Sepals{/i} connivent or somewhat spreading; dorsal free; lateral broader, sometimes very broad, adnate to the foot of the column. {i}Petals{/i} usually narrower than the dorsal sepal. {i}Lip{/i} superior, articulated to the foot of the column, 3-lobed or entire from a cuneate base. {i}Column{/i} usually short, very broad, not winged, produced into a long foot at the base; anther-bed short, truncate. {i}Anther{/i} terminal, operculate, incumbent, very convex, 1-celled or imperfectly 2-celled; pollinia 4, waxy, broadly ovate, sometimes united in pairs, affixed to a short stipes and gland. {i}Capsule{/i} oblong or fusiform, sometimes elongate.

Sepals connivent or somewhat spreading; dorsal free; lateral broader, sometimes very broad, adnate to the foot of the column. Petals like the dorsal sepal or often narrower. Lip superior, articulated to the foot of the column, base contracted, entire or 3-lobed. Column usually very short, broad, not winged, produced into a foot at the base; clinandrium short, truncate. Anther terminal, operculate, incumbent, very convex, 1-celled or imperfectly 2-celled; pollinia 4, waxy, broadly ovate, sometimes united in pairs, affixed to a short stipes and gland. Capsule oblong or fusiform, sometimes elongate. —Epiphytic herbs. Stems often short, sometimes thickened into pseudobulbs, mostly leafy. Leaves distichous, oblong or narrow, often many-nerved, contracted into sheaths at the base. Peduncle terminal, or rarely axillary, with a few sheaths below, apex paniculate or racemose. Flowers small, rarely medium-sized. Bracts small.

Epiphytic, occasionally lithophytic or terrestrial perennial herbs.Stems usually forming pseudobulbs, clustered or less commonly spaced out on a creeping rhizome, sometimes branched or superposed (emerging from nodes above the base of the previous pseudobulb), 1- to several-noded, with 1 to several leaves.Leaves linear, lanceolate, oblanceolate or elliptic, varying in texture.Inflorescence (comprising peduncle, rhachis and flowers) 1- to many-flowered, simple or branching.Floral bracts erect to reflexed, setiform, lanceolate, ovate or obovate, acute or acuminate to mucronate.Flowers usually non-resupinate, very small or medium-sized, rarely large, usually fragrant, often pubescent, green, yellow, white, pink, mauve or orange, rarely red.Dorsal sepal lanceolate to ovate; lateral sepals ± oblique, joined to the column-foot to form a mentum.Petals linear to obovate.Lip usually 3-lobed but sometimes entire, with or without a basal callus, glabrous, pubescent or farinose, often recurved, sometimes fleshy and difficult to flatten without breaking.Column porrect, usually short and stout with a ± elongate foot; pollinia 2, ovoid; stipe 1, square or sub-triangular to oblong or linear; viscidium small to large, round or ellipsoid; rostellum usually obscure, bifid in front, rarely slightly elongated or beak-like.

Epiphytic, lithophytic, or occasionally terrestrial herbs. Stem often pseudobulbous, rarely caulescent, caespitose or rarely well spaced on rhizome, one- or more-noded; rhizome simple or branched, creeping. Leaves suberect, spreading or arcuate, coriaceous to thin-textured, persistent or deciduous, linear, ligulate, oblong, elliptic, obovate or oblanceolate, acute, obtuse or acuminate; leaf base sheathing, often with an articulation. Inflorescence terminal, racemose, simple or branching, one- to many-flowered; peduncle glabrous or pubescent, often bearing one or more sterile bracts. Flowers usually non-resupinate, pubescent or glabrous on outer surface. Dorsal sepal ovate, lanceolate or oblong-elliptic, usually curving over column; lateral sepals usually spreading, oblique at base, often forming a distinct conical mentum with column foot. Petals linear, oblong, oblanceolate, or obovate. Labellum fleshy, usually trilobed, rarely entire, often strongly recurved, side lobes erect around column, midlobe often ovate and decurved, disc often callose, callus a raised, fleshy mound or a cushion of farinaceous hairs. Column fleshy, lacking wings, usually bearing a prominent column foot; anther terminal, pollinia two, ovoid, deeply cleft, attached at an acute angle to a square, oblong, linear, or triangular tegula and that to a viscidium; rostellum bifid after removal of the pollinarium, not prominent, rarely beak-like. Capsule ellipsoidal.

Small, medium-sized or rarely large epiphytic or less commonly lithophytic or terrestrial herbs. Stems often pseudobulbous, caespitose or less commonly spaced on a creeping rhizome, sometimes branched or superposed, 1–several-noded, 1–several-leaved. Leaves suberect to spreading, thin-textured, coriaceous or rarely fleshy, often distichous, linear or lanceolate to oblong-elliptic or oblanceolate, emarginate, acute, obtuse or acuminate at the apex. Inflorescence terminal, erect to pendulous, 1–many-flowered, simple or branching; branches sometimes secund; bracts suberect to reflexed, setose or lanceolate to ovate or obovate, acute or acuminate to mucronate. Flowers minute to fairly large, mostly with lip uppermost, non-resupinate, mostly rather drably coloured, ± fragrant, often pubescent. Dorsal sepal mostly porrect, lanceolate to ovate-elliptic; lateral sepals ± oblique, attached to the column-foot to form a more or less prominent mentum. Petals linear to obovate. Lip entire to 3-lobed, with or without a basal callus, glabrous, pubescent or farinose, often recurved and difficult to flatten. Column porrect, mostly short and stout, with a ± elongate foot; pollinia 2, ovoid; stipe 1, square or subtriangular to oblong or linear; viscidium small to large, circular or elliptic; rostellum mostly obscure, bifid in front, rarely slightly elongate and beak-like.

Morphology

Schill and Pfeiffer (1977) examined the pollen of seven species of Polystachya, including that of Neobenthamia. All species have convex tetrads with laevigate sculpturing.

Ecology

Polystachya species are mostly epiphytic or less commonly lithophytic and can be found in most forested and woodland areas within their range. They are absent from drier regions, particularly deserts and semi-deserts. Some species are specific in their host plants, for example, Polystachya dendrobiiflora Rchb.f. and P. johnstonii Rolfe are specific to the stems and branches of Xerophyta Juss. (Velloziaceae). Polystachya songaniensis G.Williamson grows in grass around the margins and cracks of rocky outcrops in southern Malawi. Polystachya neobenthamia grows on Xerophyta species but also on dry, sloping, exposed rock faces or on mossy ledges on precipices.

Distribution

Polystachya is a pantropical genus of some 230 species. The greatest diversity of species is found in sub-Saharan tropical Africa from the Gambia and Sierra Leone across to Ethiopia and Eritrea and south to South Africa. The genus is also well represented in Madagascar with some 40 species recorded. A few species are found in the tropical Americas and tropical Asia across to the Philippines, Taiwan, New Guinea, and northeastern Australia, all belonging to section Polystachya.

Uses

In West Africa, pseudobulbs of many species of Polystachya were reportedly used in the preparation of aphrodisiacs (Lawler 1984). Occasionally the showier species such as P. bella Summerh., P. galeata (Sw.) Rchb.f., and P. pubescens are available in the horticultural trade.

Literature

Exot. Fl. 2, t. 103 (1824), nom. conserv.

Exot. Fl. 2: t. 103 (1824); F.T.A. 7: 103 Nom. cons.

Benth. et Hook. f. Gen. Pl. iii. 540.

Exot. Fl. 2: t. 103 (1824), nom. conserv.

Distribution Map

 
  • Native distribution
  • Introduced distribution
Found in
  • Africa East Tropical Africa Kenya
  • Tanzania
  • Uganda
  • Northeast Tropical Africa Chad
  • Eritrea
  • Ethiopia
  • Sudan
  • South Tropical Africa Angola
  • Malawi
  • Mozambique
  • Zambia
  • Zimbabwe
  • Southern Africa Cape Provinces
  • KwaZulu-Natal
  • Northern Provinces
  • Swaziland
  • West Tropical Africa Benin
  • Burkina
  • Ghana
  • Guinea
  • Guinea-Bissau
  • Ivory Coast
  • Liberia
  • Mali
  • Nigeria
  • Senegal
  • Sierra Leone
  • Togo
  • West-Central Tropical Africa Burundi
  • Cameroon
  • Central African Republic
  • Congo
  • Equatorial Guinea
  • Gabon
  • Gulf of Guinea Is.
  • Rwanda
  • Zaire
  • Western Indian Ocean Comoros
  • Madagascar
  • Mauritius
  • Réunion
  • Seychelles
  • Asia-Temperate China China South-Central
  • Asia-Tropical Indian Subcontinent India
  • Sri Lanka
  • Indo-China Andaman Is.
  • Laos
  • Nicobar Is.
  • Thailand
  • Vietnam
  • Malesia Borneo
  • Jawa
  • Lesser Sunda Is.
  • Malaya
  • Maluku
  • Philippines
  • Sulawesi
  • Sumatera
  • Northern America Mexico Mexico Gulf
  • Mexico Northeast
  • Mexico Southeast
  • Mexico Southwest
  • Southeastern U.S.A. Florida
  • Southern America Brazil Brazil North
  • Brazil Northeast
  • Brazil South
  • Brazil Southeast
  • Brazil West-Central
  • Caribbean Bahamas
  • Cayman Is.
  • Cuba
  • Dominican Republic
  • Haiti
  • Jamaica
  • Leeward Is.
  • Netherlands Antilles
  • Puerto Rico
  • Trinidad-Tobago
  • Venezuelan Antilles
  • Windward Is.
  • Central America Belize
  • Costa Rica
  • El Salvador
  • Guatemala
  • Honduras
  • Nicaragua
  • Panamá
  • Northern South America French Guiana
  • Guyana
  • Suriname
  • Venezuela
  • Southern South America Argentina Northeast
  • Argentina Northwest
  • Paraguay
  • Western South America Bolivia
  • Colombia
  • Ecuador
  • Peru
Introduced into
  • Pacific North-Central Pacific Hawaii

Included Species

  Bibliography

  • 1 Mytnik-Ejsmont, J. (2011). A monograph of the subtribe Polystachyinae Schltr. (Orchidaceae): 1-400. Fundacja Rozwoju Uniwersytetu Gdanskiego.
  • 2 Mytnik-Ejsmont, J. & Baranow, P. (2010). Taxonomic study of Polystachya Hook. (Orchidaceae) from Asia. Plant Systematics and Evolution 290: 57-63.
  • 3 Govaerts, R. (2003). World Checklist of Monocotyledons Database in ACCESS: 1-71827. The Board of Trustees of the Royal Botanic Gardens, Kew.
  • 4 P.J. Cribb (1984) Orchidaceae. Flora of Tropical East Africa 0 (0)
  • 5 Pridgeon, A.M., Cribb, P.J., Chase, M.W. & Rasmussen, F.N. Genera Orchidacearum: Volume 6. Epidendroideae (Part Three). (Oxford University Press: 2014).
  • 6 Hooker, W.Jackson Original publication of Polystachya. 2, (1824).

 Information From

Flora Capensis
http://apps.kew.org/efloras/
Flora Capensis. Published on the Internet; http://apps.kew.org/efloras/
Flora of Tropical Africa
http://apps.kew.org/efloras/
Flora of Tropical Africa. Published on the Internet; http://apps.kew.org/efloras/
Flora Zambesiaca
http://apps.kew.org/efloras/
Flora Zambesiaca. Published on the Internet; http://apps.kew.org/efloras/
Flora of Tropical East Africa
http://apps.kew.org/efloras/
Flora of Tropical East Africa. Published on the Internet; http://apps.kew.org/efloras/
Flora of West Tropical Africa
http://apps.kew.org/efloras/
Flora of West Tropical Africa. Published on the Internet; http://apps.kew.org/efloras/
WCS higher taxonomy
  • F All Rights Reserved
World Checklist of Selected Plant Families
http://apps.kew.org/wcsp/
WCSP 2014. 'World Checklist of Selected Plant Families. Facilitated by the Royal Botanic Gardens, Kew. Published on the Internet; http://apps.kew.org/wcsp/ Retrieved 2011 onwards
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