Orchids of New Guinea

Genus Rhomboda

Rhomboda Lindl., J. Linn. Soc., Bot. 1 (1857) 181

Sympodial terrestrial plants. Stem elongated, slightly succulent, basal part creeping, forming a rhizome, apical part erect, few-leaved. Leaves crowded at the stem apex, sheathing at the base, glabrous, persistent, convolute, dark green or brownish, with a white or reddish mid-vein, herbaceous. Inflorescence a terminal, many-flowered raceme. Flowers small, usually only partly resupinate (lip pointing sideways), brownish with white petals and lip. Sepals free. Petals free, about as long as the dorsal sepal, usually cohering at the apices. Lip not spurred, not mobile, at the base with 2 warts, inside in the middle with two closely parallel crests, outside laterally with a low keel. Column in front with two longitudinal lamellae. Column-foot absent. Pollinia sectile, caudicles present, stipe absent, viscidium present. Stigma with 2 clearly separated lobes.

Distribution:

Tropical continental Asia, Malaysia, Indonesia, the Philippines, Papua New Guinea, Australia, Solomon Islands. About 20 species; in New Guinea about 5 species.

Habitat:

Terrestrial in evergreen hill and montane forest.

References:

Ormerod, P. 1995. A reinstatement of Rhomboda Lindl. (Orchidaceae subtribe Goodyerinae). Orchadian 11: 323-339.
Pridgeon, A. M., P.J. Cribb, M.W. Chase & F.N. Rasmussen (Eds.). 2003. Genera Orchidacearum, Volume 3: Orchidoideae (Part 2), Vanilloideae. Pp. 142-145. Oxford University Press, Oxford.

Classification:

Subfamily Orchidoideae
Tribe Cranichideae
Subtribe Goodyerinae
Genus Rhomboda

Notes:

The species of this genus are usually referred to Anoectochilus or Hetaeria. They differ from Anoectochilus in that the lateral crests on the lip are not toothed or fringed, from Hetaeria in that the flowers are at least partly resupinate. In Hetaeria there are two groups of two or more papillae at the base of the lip; in Rhomboda there are two solitary warts. The leaves of Hetaeria species do not have a white or red mid-vein, which always seem to be present in Rhomboda. Zeuxine is also closely related, but differs in that the lip lacks the crests seen in Rhomboda, and by the leaves lacking a white or pink mid-vein. Moreover, it appears that the pollinia of Rhomboda are not attached to a glassy stipe, as they usually are in Zeuxine. Species of Rhomboda are probably not in cultivation, although some have rather attractive foliage.

Genus Rhomboda in New Guinea is present with 5 species and 1 variety:

Rhomboda alticola
Rhomboda alticola var. finisterrae
Rhomboda atrorubens
Rhomboda lanceolata
Rhomboda novaehiberniae
Rhomboda polygonoides