Disperis oppositifolia Sm.

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 : 60-62

4. Disperis oppositifolia Sm.

Cycl. 11, no. 6 (1819); Lindley, Gen. Sp. Orch. Pl.: 371 (1839); S . Moore in Baker , Fl. Mauritius Seych.: 331 (1877); J . de Cordemoy , Fl. La Réunion: 254 (1895); Schlechter, Bull. Herb. Boiss. 6, 12: 954 (1898) & Feddes Repert. Spec. Nov. Regni Veg. Beih. 33: 109 (1925); H . Perrier in Humbert H. (ed.) , Fl. Madag., 49 e fam., Orchidées 1: 182 (1939); Du Puy et al., Orch. Madag.: 135 (1999). — Dryopeia oppositifolia (Sm.) Thouars, Orch. Iles Afr. , t. 1 (1822); A . Richard , Monogr. Orch. Iles de France et Bourbon: 35 (1828); Bojer, Hort. Mauritius: 311 (1837). — Type: Smith s.n., La Réunion (holo-, LINN!) .

Slender terrestrial herb 6-25 cm high; tubers oblong. Leaves 2, opposite, borne on upper half of stem, 1.5-5.5 × 0.8-2 cm, lanceolate or ovate, acute, with a short petiole. Inflorescence 1-3- flowered; bracts c. 6 mm long. Flowers off white to pale pink with purple lines on the upper part of the petals; pedicel and ovary 9-12 mm long. Dorsal sepal 4.5-6(-7) × 0.5 mm, linear; lateral sepals 5-10 × 3-4 mm, joined at the base for a third to a half of their length, each with a small, sac-like spur. Petals 4.5-6(-7) × 3-3.5 mm, broadly falcate, adnate to the dorsal sepal to form a shallow hood, cordate at the base. Lip clawed, with a 3-lobed appendage, slightly pubescent, the mid-lobe short, triangular, the side lobes linear, curving back, longer than the mid-lobe but sometimes a little enlarged and rounded at the apex, 1.5-2 mm long. Rostellum arms slender up to 1.5 mm long. — Figs. 3 , 7D.

DISTRIBUTION. — Madagascar, the Comoro and the Mascarene Islands.

HABITAT. — Moisture-loving species of humid forests at low and intermediate elevations; terrestrial or on rocks by streams, sometimes in moss on the base of tree trunks, also found in riparian forest with Pandanus sp. , and sometimes in pine plantations; sea level- 1200 m.

MATERIAL STUDIED. — MADAGASCAR: Baron 129 & 4288, C Madagascar ( K!) ; Bosser 19028, S of Ambositra , P. K. 300, Jan. 1964 ( P!) ; Carlson 427, Toamasina, Nosy Mangabe, Bay of Antongil ( K, MO, P!) ; Decary 10482 & 10485, col de Maningotra, 500- 700 m, Fort-Dauphin Distr. , 4-5 Sep. 1932 ( P!) ; Jard. Bot. Tananarive 5651, Amboangy, Befandriana , 24 Dec. 1942 ( P!) ; Jard. Bot. Tananarive 6500, la Mandraka , Feb. 1941 ( P!) ; J. Hermans 3813, Fianarantsoa Prov., RN 33 from Ivato to Ambatofinandrahana , in pine forest at edge of inselberg, 14 Jan. 1996 ( K!) ; J. & C. Hermans 24/96-6, Antananarivo Prov., Angavokely, station forestière, c. 1500 m, 24 Jan. 1996 ( K!) ; J. & C. Hermans 26/96- 4, 68 km from Antananarivo, just past Mandraka dam, 26 Jan. 1996 ( K!) ; Humbert 13912, basin of the Mananara, tributary of the Mandrare , between Andohahela and Elakelaka, at Aniampanga (left side of Ankaramy ) upstream of Mahavavo , 700-800 m, Jan.- Feb. 1934 ( P!) ; Lance 38, Masoala Peninsula, headwaters of Andranotsorabe , W of Andrembona , 470 m, 19 Sep. 1993 ( K!) ; Lewis & Razafimandimbison 661, Toamasina, East coast, Betampona Réserve Naturelle Intégrale , 40 km N of Toamasina, 275-650 m, 28 Sep. 1993 ( K!, MO!, P!) ; Parker s.n., C. Madagascar, comm. Aug. 1880 ( K!) ; Perrier de la Bâthie 1861 (no. 83 de Schlechter), woods of Sambirano Valley , 800 m ( P!) ; Perrier de la Bâthie 11845, Mt. Vatovavy, basin of Mananjary , Aug. 1911 ( P!) ; Prance & Andriantiana 30764, buffer zone of Mananara Avaratra, Antanambe Biosphere Res., hills around Mahavohobe R., 25 Oct. 1994 ( K!) ; F. Rakotondrainibe 3343, Antsiranana Prov., Andapa Distr., RNI of Marojejy , 8 km NW of Manantenina, 480 m, 8 Oct. 1996 ( P!) ; Schatz 2735, Toamasina, Nosy Mangabe, 5 km S of Maroantsetra , 0-330 m, 20-25 Sep. 1989 ( K!, MO!, P!) ; Thérézien s.n., Kitsamby Forest, 20 km from Soavinandriana , Itasy , Jan. 1964 ( P!). — C OMORES: Humblot 1228, Combani Forest , Mayotte , 13 July 1894 ( P!) ; Kirk s.n., without exact loc. ( K!) ; Tinguy 944, Mt. M’tsapere, 500 m, Mayotte , 8 Sep. 1989 ( P!) . — MAURITIUS: Ayres s.n., Nov. 1861 ( K!) ; Blackburn s.n., without exact loc., rec. 17 July 1863 ( K) ; Boivin s.n., Mt. Pouce , Sep. 1849 ( P!) ; Brouard & Mulnier in MAU 11463, Mt. Bambous , 24 Oct. 1964 ( MAU!) ; Bruguières 36, without loc. (P-JU!); Colville Barclay 315, Bassin Blanc crater, 1400 ft., 28 Oct. 1967 ( K!) ; Commerson 235, without loc. ( P!, P-JU 3889!) ; Edgerley in MAU 13049, Bassin Blanc , 8 Oct. 1967 ( MAU!) ; Gueho in MAU 11419, Kanaka ( MAU!) ; Gonan s.n., La Roau ( K!) ; Herb. L. C. & A. Richard s.n., without loc. ( P!) ; Vaughan 1762, Macabe ( K!, MAU!) ; Vaughan 3032, Bassin Blanc ( K!, MAU!) ; Vesco s.n., 1850 ( P!) . — LA RÉUNION: Cadet 1623, Mare Longue, St. Philippe , 25 Sep. 1968 ( P!, REU!) ; Cadet 3739, le Grand Brûlé, 120 m ( REU!) ; Cadet 6188, Mare Longue, St. Philippe , 300 m ( REU!) ; Cadet 6543, le Grand Brûlé forest ( REU!) ; Dumont D’Urville , without loc. ( P!) ; Herb. Desvaux , without loc. ( P!) ; de Cordemoys. n., Bras Panon ( MARS!) ; Thouars s.n., without loc. ( G!, P!) .

The flowers of this species are white, pale rose or lilac or white with sepals striped with red, magenta or mauve. The terminal appendage of the lip is variable. The mid-lobe is often short and triangular, but it can be elongated into a point at the glabrous tip (Dumont-D’Urville, La Réunion). The two side lobes are curved, rounded at the tips or more or less spathulate at the end. The pubescence is always papillose and short on the two lateral lobes and the base of the mid-lobe, but the tip of the latter can be glabrous.

In many localities this orchid is more or less robust and the size of the flower is variable.It can be locally common, often being found in small colonies.

— Disperis oppositifolia var. mascarenensis Bosser , var. nov.

A varietate typica appendice labelli trilobati longe ciliato, lobo medio supra glabro et lobis lateralibus ad apicem rotundatis satis distinguenda. — Figs. 6I , 7E.

TYPUS. — Bosser 21622, La Réunion, Ravine Grande Chaloupe, Mt. St. Denis, 17 Mar. 1974 (holo-, P!) .

DISTRIBUTION. — La Réunion and Mauritius, endemic to the Mascarenes. Found only in Ravine Grande Chaloupe on La Réunion, where the typical variety also grows. From Mauritius a single specimen, Commerson s.n., has been seen. The presence of var. mascarenensis on Mauritius is therefore doubtful.

HABITAT. — Under trees in light, semi-dry forest of the west; c. 500 m.

MATERIAL STUDIED. — LA RÉUNION: Bosser 21622, Ravine Grande Chaloupe, Mt. St. Denis, 17 Mar. 1974 ( P!) ; Bosser 22369, Ravine Grande Chaloupe, 7 Mar. 1978 ( P!) ; Friedmann 2136, Ravine Grande Chaloupe, Mar. 1973 ( P!) . — MAURITIUS: Commerson 235, without loc. ( P!) .

The morphology of the flower of this variety is very similar to that of typical D. oppositifolia with the elongated lateral sepals united and contracted into a narrow cuneiform base. However, the features of the terminal appendage of the lip are distinctive. This appendage is also trilobed but it has longer papillae; the upper side of the mid-lobe is glabrous and lacks any short, dense, papillose hairs. Moreover, rounded side lobules frame the base of the mid-lobe. The inflorescence also has many more flowers, up to 12.

Figures

Fig. 3. — Disperis oppositifolia: A, flowering plant; B, flower and bract; C, hood, side view; D, dorsal sepal; E, lateral sepals; F, petal; G, column and lip, front view; H, column and lip, back view; I, column and lip, side view; J, lip, side view; K, lip, back view. (Schatz 2735, K).

Fig. 7. — Flowers of Disperis species: A, D. hildebrandtii; B, D. saxicola; C, D. discifera; D, D. oppositifolia var. oppositifolia; E, D. oppositifolia var. mascarenensis; F, D. masoalensis. (A, D, F, photos J.-N. LABAT; B, C, E, photos J. BOSSER).

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).