Polystachya, W.J.Hooker, 1824

Peraza-Flores, Lizandro N. & Carnevali, Germán, 2012, Things are seldom what they seem: the nomenclature of Polystachya masayensis (Orchidaceae), Phytotaxa 50 (1), pp. 51-54 : 52-53

Key to distinguish Central American Species of Polystachya (South of the Tehuantepec Isthmus)

1. Rachis of the inflorescence and pedicellate ovary densely hispid-puberulous ( figure 1B ).......................................... 2

- Rachis of the inflorescence and pedicellate ovary glabrous or sparsely pubescent ..................................................... 3

2. Central lobe of the labellum transversely elliptic-suborbicular to transversely subquadrate or transversely oblong, always broader than long, apically truncate, truncate-rounded to deeply emarginate ............................. P. masayensis

- Central lobe of the labellum lanceolate to ovate, always longer than wide, apically rounded to broadly acute ........... ......................................................................................................................................................................... P. elatior

3. Base of labellum straight or slightly cuneated. Central lobe of labellum half or more than half the length of the labellum, lateral lobes well developed ........................................................................................................... P. caracasana

- Base of the labellum unguiculated. Central lobe of labellum less than half the length of the labellum, lateral lobes small and poorly developed ......................................................................................................................................... 4

4. Flowers small-sized (4.30–4.70 mm long), column foot small (0.30–0.40 mm long), callus of the labellum rounded and short (ca. 0.40 mm high), lateral lobes small and well-developed .......................................................... P. clavata

- Flowers medium-sized (6.20–9.60 mm long), column foot large (0.90–1.20 mm long), callus of the labellum rounded and tall (0.80–1.10 mm high), lateral lobes small and poorly developed ......................................... P. lineata

Figures

FIGURE 1. A–C. Polystachya masayensis, A. Habit. B. Inflorescence detail. C. Labellum outline, based on C.H. Lankester 1081 (AMES). D. Polystachya elatior, labellum outline, based on L.O. Williams et al. 23880 (EAP-5624). A–B, Modified from Romero & Carnevali (2000) with permission of the authors. C–D. Drawn by L. Peraza.