AFRICAN

ORCHIDS

Polystachya Hook., Exot. Fl. 2: t. 103 (1824), nom. cons.
Heterotypic Synonyms:
Dendrorkis Thouars, Nouv. Bull. Sci. Soc. Philom. Paris 19: 314 (1809).
Epiphora Lindl., Companion Bot. Mag. 2: 201 (1837).
Dendrorchis Thouars ex Kuntze, Revis. Gen. Pl. 2: 658 (1891), orth. var.
Nienokuea A.Chev., Compt. Rend. Hebd. Séances Acad. Sci. 220: 634 (1945).
Disperanthoceros Mytnik & Szlach., Richardiana 7: 65 (2007).
Geerinckia Mytnik & Szlach., Richardiana 7: 62 (2007).
Szlachetkoella Mytnik, Richardiana 7: 57 (2007).
Dendrobianthe (Schltr.) Mytnik, Richardiana 8: 24 (2008).
Epiphorella Mytnik & Szlach., Richardiana 8: 13 (2008).
Unguiculabia Mytnik & Szlach., Richardiana 8: 19 (2008).
Description:
Sympodial, usually epiphytic but several lithophytic, cither occasionally or consistently; rarely terrestrial. Pseudobulbs usually well defined, set close together, forming clumps or chains, variable in shape from small and nutlike, to conical, spindle-shaped, and fiat and coin like, one-to several-leaved, often deciduous in the dry season. Plants in section Caulescentes have reed like stems not swollen at the base.
Inflorescence terminal on the pseudobulb (unlike in Bulbophyllum, where it anses from the base), one- to many-flowered. Flowers small to medium-sized, commonly white, green, yellow, or yellow-green, but sometimes pink, mauve, purple, orange, or even red; flowers usually scented, most often with a primrose like perfume, but others with a strong, intensely sweet scent.
Flowers non-resupinate; however, if a plant has an arching or pendent inflorescence, with the tip pointing down, the hp will seem to be at the bottom of the flower. Flowers usually rather bell-shaped, but in a few species they open widely to present an almost flat flower. Lateral sepals joined at the base to the column foot to form a chinlike structure called the mentum. The shape of the mentum is important in the identification of species; it is often low and rounded, but can be very prominent, occasionally forming a spur like structure. Petals small. Lip usually trilobed, entire in some species, often recurved, sometimes very fleshy, usually with a callus at the junction of the lobes. Column usually short and stout, with a prominent foot; pollinia two, stipes one, viscidium one.
Distribution:
A genus of ca. 200 species, pantropical but mostly African.
Cultivation:
Many species of Polystachya are well worth growing, particularly the smaller ones. Most are compact plants that take up little space with long-lasting, scented fiowers. Plants can be mounted on bark, but need high humidity and regular misting when in growth as the fine roots dry out quickly. These orchids are more successfully grown in pots in a medium bark mix that should not be allowed to remain wet. Deciduous species in particular should be kept pretty dry until new growth starts. Some species flower on an old pseudobulb after the leaves have fallen, while others flower on the newly developing shoots. Plants can easily be divided when they fill their pot, but this should only be done when necessary as they are all happier when in large clumps. Almost all species do well in intermediate temperatures and moderate shade, but lowland species should thrive at intermediate to warm temperatures, while those from montane areas prefer temperatures on the cool side of intermediate.
Notes:
The genus Polystachya was established by Sir William Hooker in 1825. The name comes from the Greek words polys (many) and stachys (a spike or ear of grain), referring either to the clumps of many stems characteristic of most species, or to the appearance of an inflorescence in bud.
Polystachya is by far the largest genus of epiphytic orchids found in Africa. Although it does not have as many species worldwide as does Bulbophyllum, Polystachya is predominantly an African genus: almost 200 species are found throughout the tropics, 160 of which occur in Africa. About 20 species are known from Madagascar. It is difficult to give exact figures, for while some species are widespread, others are narrow endemics.
The last revision of the entire genus was made by the German botanist Fritz Kränzlin in 1926, when he divided it into a number of sections. Since then, many new species have been described, some sections have been revised, and some new sections have been created, notably by P. J. Cribb (1978), but a worldwide revision is much needed.
A new revision of the subtribe Polystachyinae Schltr. (Orchidaceae). By Jonna Mytnik Ejsmont
Ph.D. University of Gdansk • Department of Plant Taxonomy and Nature Conservation 2011 which I have chosen to follow here below:
Polystachya species are classified into thirteen sections. Apart from with sect. Polystachya which is pantropical, all sections are confined to Africa and Madagascar with two endemic to Madagascar and the Indian Ocean islands.
Key to Polystachya in Africa an Madagascar:
But this genus below are not accepted by:
Govaerts, R. (2003). World Checklist of Monocotyledons Access: 08/12/2013. The Board of Trustees of the Royal Botanic Gardens, Kew.
Unguiculabia Mytnik & Szlach., Disperanthoceros Mytnik & Szlach. , Szlachetkoella Mytnik Epiphorella Mytnik & Szlach., Isochilostachya Mytnik & Szlach, Dendrobianthe (Schltr.) Mytnik, Neoburttia Mytnik, Szlach. & Baranow, Chelystachya Mytnik & Szlach., Epiphorella Mytnik & Szlach.,
Therefore have I set this genus with the old section in the key of the Polystachya in Africa an Madagascar.
Bibliography and References:
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Mytnik Ejsmont J. 2007 Contribution a la revision de Polystachyinae Schlechter (Orchidaceae). 1-Szlachetkoella Mytnik. Richardiana 7. (2): 55-60. Fr (En)
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Mytnik-Ejsmont, J. & Szlachetko, D.L. (2008) Contribution à la révision de Polystachyinae Schlechter (Orchidaceae). 4. Epiphorella Mytnik & Szlachetko. Richardiana, 8(1), 12-17.
Mytnik-Ejsmont, J. (2007) Contribution à la révision de Polystachyinae Schlechter (Orchidaceae). 1- Szlachetkoella Mytnik. Richardiana, 7(2), 55-60.
Mytnik-Ejsmont, J. (2008) Contribution à la révision de Polystachyinae Schlechter (Orchidaceae). 6. Dendrobianthe Mytnik. Richardiana, 8(1), 23-27.
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Stévart, T. & Geerinck, D. (2000) Four new taxa of Orchidaceae in the genera Liparis, Bulbophyllum, Polystachya and Calanthe discovered from Sao Tome and Principe. Systematics and Geography of Plants, 70(1), 141-148.
Stévart, T. & Nguema, N. (2004) Trois espèces et quatre combinaisons nouvelles de Polystachya (Orchidaceae) du Cameroun, de Guinée Equatoriale et du Gabon. Adansonia, 26(2), 217-233.
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