Bijdr. (1825) 372
Sympodial epiphytic or terrestrial plants. Stem elongated, often branching. Leaves many, sheathing at the base, sheath hairy or not, often more or less warty, margins often fimbriate-laciniate, blade glabrous, dorso-ventrally flattened, sometimes almost terete, articulate, duplicate, stiffly thin-textured to carnose. Inflorescence terminal, a raceme or carrying a single flower, subtended by one or more membranous sheaths (spathes). Flowers small to rather large, resupinate or not, variously coloured but predominantly white, the lip often with a conspicuous blackish, red, green or yellow spot near the apex. Lateral sepals, and sometimes also the dorsal sepal connate at the base. Petals free, often fairly similar to the dorsal sepal, but sometimes distinctly broader, rarely narrower. Lip adnate to the column, spurred, not mobile. Column relatively short and thick, with deeply concave clinandrium and cup-like stigma; column-foot present or absent. Pollinia 4, solid-waxy, caudicles present, stipe absent, viscidium present or absent.
Thailand, Java, Sulawesi, Moluccas, New Guinea, Solomon Islands, New Caledonia, Vanuatu, Fiji, east to Samoa. About 100 species; in New Guinea c. 90 species.
Epiphytes in lowland and montane forest, at higher altitudes also terrestrial. Most abundant above 2000 m.
In terms of biomass Glomera is one of the predominant orchid genera in the montane forests of New Guinea. When not in flower most species resemble a small ericaceous shrub rather than an orchid. The inflorescences are always terminal, often at the apex of short lateral branches. Branches of different age and length often flower simultaneously. The inflorescences are either one-flowered or consist of two to many flowers seemingly arranged in a head. This head-like inflorescence is in fact a strongly abbreviated raceme; it is not, like in the superficially similar genus Agrostophyllum, a fascicle of several short inforescences, although it has often been wrongly interpreted as such. Glomera is not at all closely related to Agrostophyllum. Surprisingly, recent DNA studies by Cameron, Gravendeel and others, place Glomera quite close to Coelogyne, with which there are few morphological similarities. At species level Glomera is taxonomically among the most difficult genera in New Guinea. Like in some other genera in this region (e.g. Epiblastus, Mediocalcar, Phreatia and Ceratostylis) species with totally different habit may have almost identical flowers. Species of Glomera are rarely cultivated, even though some are very pretty. Experience in the Hortus Botanicus in Leiden has shown that plants imported from the wild are hard to establish, but once established they are not too difficult, provided they are not allowed to dry out much at any time.
Two sections can conveniently be distinguished: sect. Uniflorae with 1-flowered inflorescences, and sect. Glomera with 2- or more-flowered inflorescences. It seems doubtful whether this corresponds with the main branches in the phylogeny of the genus. The former genera Glossorhyncha, Giulianettia, Ischnocentrum and Sepalosiphon all belong to sect. Uniflorae, which is the most diverse of the two sections.