Octarrhena Thw.,
Enum. Pl. Zeyl. (1861) 305
Small sympodial epiphytic or terrestrial plants. Stem elongated, not swollen, sometimes laterally compressed. Leaves c. 5 to many, distichous, sheathing at the base, glabrous, laterally compressed or filiform-terete, articulate or not, duplicate, stiffly thin-textured to carnose. Inflorescence lateral, a raceme or carrying a single flower. Flowers small to very small, resupinate, often orange-brown, greenish, yellowish or whitish. Sepals connate at the base. Petals free, almost always very much shorter than the sepals. Lip without spur, not mobile. Column-foot absent. Pollinia 4 or 8, solid-waxy, caudicles present or absent, stipe absent, viscidium present.
Distribution
Sri Lanka, Southeast Asia, Malesia, east to Fiji; about 40 species.
Distribution in the Philippines
Luzon (Mt. Province, Ifugao, Benguet, Bataan, Camarines), Leyte, Negros, Mindanao (Bukidnon, Surigao, Agusan, Davao, Cotabato); 4 species.
Habitat
Epiphytes in lowland and montane forest.
Notes
Although related to Phreatia and Thelasis, species of Octarrhena are often mistaken for members of the genus Oberonia, as the plants look rather similar. They have laterally flattened leaves, like Oberonia, but are easily distinguished by the lateral, not terminal inflorescences. This genus is of no horticultural value.