Polystachya in Africa an Madagascar
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.
A key to the sections:

1 Pseudobulbs 1-leaved 2
1b Pseudobulbs 2-to many-leaved 4
2 Leaf linear, grass-like; pseudobulbs clustered; rostel-lum elongate, beak-like section Bicalcaratae
2b Leaf oblong, obovate, ovate or ligulate; pseudobulbs dustered or not; rostellum truncate or slightly notched 3
3 Rachis pubescent, pseudobulbs 2-noded section Caleatae
3b Rachis glabrous; pseudobulbs many-noded section Cultriformes
4 Leaves absent at the anthesis 5
4b Leaves present at the anthesis 6
5 Rachis covered with papery sheaths; lip longer than wide or as long as wide section Steudnerae
5b Rachis not covered with papery sheaths; lip markedly wider than long section Eurychilae
6 Stem reed-like, pseudobulbs absent, leafy in upper half; pseudobulbs absent section Caulescentes
6b Pseudobulbs present, of different shape 7
7 Stems thickened into pseudobulbs after the anthesis; pseudobulbs disc-like, conical, ovate or cylindric section Humiles
7b Stems thickened into pseudobulbs before the anthesis; pseudobulbs fusiform to conical 8
8 Mentum absent; lip with high, horn-like callus; column foot rudimentary; plants endemic to Madagascar section Oreochares
8b Mentum present; lip with a fleshy callus if any; column foot prominent 9
9 Inflorescence dense and compact; flowers tiny to small, subglobose; rostellum elongate, ribbon-like or furculate section Calluniflorae
9b Inflorescence not compact; flowers medium-sized, not globose; rostellum truncate or notched 10
10 Stems superposed 11
10b Stems not superposed 12
11 Terrestrial plant, bamboo-like; sepals 12-14 mm long; lip 8-13 mm long section Dimorphocaules
11b Epiphytic plant; sepals 1-6 mm long or 20-25 mm long; lip 1.5-6 mm long or 15-18 mm long section Superpositae
12 Flowers of dull colours; anther partitions obscure section Polystachya
12b Flowers brightly coloured (orange, yellow, white, cream, pink or purple); anther partitions prominent; plants endemic to Madagascar, Comoros and Seychelles section Pseudomonophyllae

Unguiculabia Mytnik & Szlach. 5 species. see A key to the species of Unguiculabia
Disperanthoceros Mytnik & Szlach. = Polystachya anthoceros la Croix & P.J.Cribb
Szlachetkoella Mytnik Epiphorella Mytnik & Szlach. = Polystachya section Aporoidea Kränzlin
Isochilostachya Mytnik & Szlach.= Polystachya section Isochiloides
Dendrobianthe (Schltr.) Mytnik,= Polystachya section Dendrobianthe Schlechter
Neoburttia Mytnik, Szlach. & Baranow,=  Polystachya longiscarpa Summerh.
Chelystachya Mytnik & Szlach.= Polystachya section Affines
Epiphorella Mytnik & Szlach.,= Polystachya section Elasticae
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