Liparis longicaulis Ridl., J. Linn. Soc., Bot. 21: 461 (1885).
Leptorkis longicaulis (Ridl.) Kuntze, Revis. Gen. Pl. 2: 671 (1891).
Large terrestrial or rarely epiphytic plant up to 35 cm tall, rhizome short, repent or slightly ascending, roots more or less finely villous. Pseudobulbs often clustered, stem-like, up to 25 cm long, 5 – 11 mm diam., distinctly tetragonal or angular-winged when alive, enveloped by several overlapping greyish-white sheaths along its length, carrying two leaves (very rarely three) at the apex. Leaves broadly ovate, rounded to sub-cordate at the base, subsessile or shortly petiolate, attenuate to acuminate at the tip, undulate, crenulate along the margins, glaucous green to pale green, 5 – 9 × 3.2 – 5.5 cm. Inflorescence erect carrying up to 10 flowers but generally fewer, often exceeding the length of the stem, 10 – 24 cm. Peduncle about twice the length of the rachis, c. 2 mm in diam., with one or two cordate to lanceolate peduncle sheaths up to 10 × 5 mm. Rachis about ½ to 1/3 of the inflorescence, laxly-flowered. Floral bracts lanceolate, the base more or less cordate, 7 – 10 × 2 – 4.5 mm. Flowers large, up to 24 × 18 mm, olive green to dark green becoming more yellow with age, the lip with a darker disk, column and ovary white, pollen yellow, flowers opening in succession, the upper ones sometimes cleistogamous or deformed. Pedicel and ovary somewhat ridged to winged, 11 – 17 × 0.6 – 1.8 mm. Dorsal sepal erect or curved forward a little at the apex, linear to ligulate, attenuate, margins recurved, 16 – 22 × 1.5 – 3.5 mm. Lateral sepals forming a platform below the lip, sometimes partly fused into one blade, broadly falcate, the outer margins curved upwards, 10 – 18 × 5 – 7.9 mm. Petals narrow linear, recurved, the margin incurved, 10 – 15 × 0.6 – 1.3 mm. Lip oval to broadly ovate, the base with short rounded wings then broadening into an obtuse anterior lobe with an irregular dentate margin, callus at the base fairly indistinctly bilobed-rounded, 10 – 13.2 × 5.5 – 9.9 mm. Column slender, slightly arching, wings long, obtuse, 4.5 – 6.9 × 1 – 1.9 mm. Anther generally with a short angular-obtuse beak, 1.1 – 1.6 × 0.6 – 1.3 mm. Pollinia two pairs united at the tip by an obsolete viscidium, c. 0.7 × 1 mm.
Referring to the long distinct pseudobulb-stem.
This is a large plant with long angular (sometimes not obvious in herbarium material) pseudobulbs, almost entirely covered by white sheaths, broadly ovate leaves, and large flowers with an obtuse lip, crenulate at the front, and a small rounded callus at the base.
It bears some similarity to Liparis gracilipes but its leaves are much thinner and broadly oval vs elliptic, the lip ovate vs suborbicular, the callus indistinct vs tridentate. There is also some similarity to L. zaratananae but again the pseudobulbs are angular vs rounded, the leaves broadly ovate vs ovate-elliptic and the lip ovate vs oval. Historically it has been confused in the field and in herbaria with the newly described L. chantaliae but it is distinct because of its angular (vs rounded) pseudobulbs covered by papery sheaths, short rhizome, slightly smaller flowers, lip with an obtuse tip (vs attenuate), indistinct callus and the less acute beak of the anther.
Evergreen forest, moss forest, riverine forest, degraded forest. Often amongst dense undergrowth in deep shade in humus-rich and moist soil. Altitude: 800 – 1800 m.
Flowering in January-April.
This species is slightly variable as to the form of the labellum, oblong or more or less widely oval, and sometimes the same and subtrilobed in the apical flowers. It has been noted that the flowers are scented (Hermans 3997).
As given for the genus.
Flora of Madagascar: vascular plants: 49th family, Orchids / by H. Perrier de La Bathie; published under the auspices of the government of Madagascar and under the direction of H. Humbert; English revision and translation by Steven D. Beckman; Malaxideae (Orchidaceae) in Madagascar, the Mascarenes, Seychelles and Comoro Islands Kew Bulletin volume 75, Article number: 1 (2020)
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