Disperis cordata Sw.

Croix, Isobyl la, Bosser, Jean & Cribb, Phillip J., 2002, The genus Disperis (Orchidaceae) in Madagascar, the Comores, the Mascarenes and the Seychelles, Adansonia (3) 24 (1), pp. 55-87 : 78-79

17. Disperis cordata Sw.

Kongl. Vetensk. Acad. Nya Handl. Stockholm 21:

218 (1800); Lindley, Gen. Sp. Orch. Pl.: 371 (1839);

S. Moore in Baker, Fl. Maurit. and Seychelles: 331

(1877); Schlechter, Bull. Herb. Boiss. 6: 955

(1898). — Type from Mauritius .

Disperis discolor (Thouars) Frappier, Cat. Orch. La Réunion: 10 (1880); de Cordemoy, Fl. La Réunion: 254 (1895). — Dryopeia discolor Thouars, Orch. Iles Afr. : t. 2 (1822); A. Richard , Monogr. Orchid. Iles de France et Bourbon: 36 (1828). — Type: Thouars, Orch. Iles Afr.: t. 2 (1822) (lecto-, chosen here).

A slender glabrous terrestrial herb, 8-20 cm tall. Stem violet. Tubers 2, subsphaerical or ovoid, pubescent, 0.7-1,2 cm long. Leaves 2, alternate, sessile, narrowly ovate or ovate, acute at the apex, cordate or amplexicaul at the base, (1-)1.5-3.7 × 0.7-1.4 cm, the lowermost inserted in the basal quarter to middle of the stem; upper surface dull green with a median pale nerve; lower face violet. Inflorescence 1-2(-3)-flowered; floral bracts broadly ovate, cordate, foliaceous, the lowermost much larger, 0.8-1.5 cm long. Flowers rose-coloured or white with a streak of purple on the petals, dorsal sepal with some violet spots on the inner face towards the base. Dorsal sepal linear, one-nerved, 7-8 mm long; lateral sepals obliquely ovate, obtuse, 7-10 × 4-4.5 mm, 5-nerved, united at the base for about half their length, each furnished towards the inner margin with a short obtuse spur. Petals obliquely ovate, forming with the dorsal sepal a slightly concave hood, 8 × 6-6.5 mm. Lip adnate to the column, linear and ascending in the basal part, the terminal part free, bifid at the base, with slender arcuate branches, 1.5 mm long, tomentose-papillose; the terminal appendage ovate, 1-1.5 mm long, curved on the upper surface and bearing a yellow tomentose indumentum, stalked, the stalk linear, flat, 2-2.2 mm long. Rostellar arms 1.5 mm long, slightly dilated at the apex. — Fig. 6B.

DISTRIBUTION. — La Réunion, Mauritius; endemic to the Mascarenes.

HABITAT. — Under trees in semi-dry forest; 400-1500 m.

MATERIAL STUDIED. — LA RÉUNION: Bernardi 14988, La Grande Chaloupe, 400-500 m, 11 Jan. 1975 ( G!) ; Bosser 21031, path to Ilet à Guillaume, 31 Dec. 1971 ( P!) ; Bosser 21111, Ravine du Chaudron, 8 jan. 1972 ( P!) ; Bosser 21623, Ravine Grande Chaloupe, 17 Mar. 1974 ( P!) ; Bosser 22352, ibid., 1 Mar. 1978 ( P!) ; Cadet 1900, Bras Sec, Cirque de Cilaos , c. 1500 m, 7 Feb. 1969 ( P!) , Delteil s.n., without exact loc. ( P!); Friedmann 1541, Ravine of Marquet , Dos d’Âne, 700 m, Feb. 1972 ( P!) ; Friedmann 2137, Ravine Grande Chaloupe, 550 m, Mar. 1973 ( P!) ; de CordemoyC. 1, Bois de Nèfles , 700-800 m, 1870 ( MARS!) . — MAURITIUS: Bosser 21896, les Trois Mamelles, 20 Apr. 1974 ( P!) ; Commerson s.n., without exact loc. ( G!, P!).

Although we have not seen the type, it is described in the protologue as having connate lateral sepals and a bilobed lip with a recurved, spathulate appendage. Given that the Mauritian species are well known, we are sure that it is the same as D. discolor , a species subsequently described by DU PETIT THOUARS.

We have not managed to locate the type specimen of D. discolor . P.THOUARS’ plate in Orchidées des îles Australes d’Afrique (1822) has been chosen here as the lectotype. The fusion of the lateral sepals is well illustrated there and, as shown in “de”, the appendage of the lip has two arcuate branches.

The habit is very similar to that of D. tripetaloides but the flowers are very distinct.

FRAPPIER, in his Catalogue, cited D. discolor Frappier , not stating explicitly that this name was based on Dryopeia discolor of THOUARS. But in his introduction, he gave a list of several works he used to compile his catalogue and cited the publication of THOUARS, Orchidées des îles Australes de l’Afrique (1822). As he did not retain the genus Dryopeia then it is evident that FRAPPIER in using the name Disperis discolor made an indirect citation of Dryopeia discolor Thouars. The combination Disperis discolor (Thouars) Frappier is accordingly retained as used by Jacob DE CORDEMOY in Flore de La Réunion: 254 (1895).

REICHENBACH, in Fl. Germ. Recens. Orch. 13 & 14, t. 354, figs. 27-30 (1850), illustrated a flower of a plant said to be D. cordata Sw. This flower, and particularly the terminal appendage of the lip, does not correspond to any of the Mascarene species of Disperis . The origin of the plant used for this drawing is not stated.

Figures

Fig. 6. — Appendage of lip: A, Disperis majungensis (Perrier de la Bâthie 13038); B, Disperis cordata (Cadet C11, in alcohol); C, Disperis hildebrandtii (Hildebrandt 3158); D, Disperis ciliata (Humbert & Capuron 25002); E, Disperis lanceana (Lance s.n.); F, Disperis saxicola (Bosser 17168); G, Disperis humblotii (Humblot 1592); H; Disperis perrieri (Humbert & Capuron 25758); I, Disperis oppositifolia var. mascarenensis (Bosser 21622).