Bijdr. (1825) 380
Sympodial terrestrial plants with short to very short rhizomes. Pseudobulbs present or not, consisting of one to several internodes, 1- or few-leaved, when absent stem elongated, few- to many-leaved. Leaves at the base sheathing or not, glabrous, plicate, deciduous or not, convolute, green, sometimes purple, or with silvery green longitudinal bands, or with pale yellow spots, thin-textured. Inflorescence lateral from the base of the plant, a many-flowered raceme, with the flowers opening in succession. Flowers medium-sized, resupinate. Sepals free. Petals free, about as long as the sepals, but usually somewhat narrower. Lip without spur, elastically hinged to the column, sensitive (see notes below). Column-foot very short or absent. Pollinia 4, solid, caudicles present, stipe absent, viscidium present.
Southeast Asia, Malaysia, Indonesia, the Philippines, Papua New Guinea, Solomon Islands. About 40 species; in New Guinea about 15 species.
Terrestrial in lowland and montane forest, usually in shady locations.
This highly distinctive genus is easily recognised by the relatively small sensitive lip, which snaps upward against the column when touched, never to resume its original position unless forced to do so. Although most species of Plocoglottis are not overly attractive and rarely seen in collections they are well worth cultivating for their curiosity value.
Partly based on vegetative characters and partly on floral ones, Plocoglottis can easily be divided into three sections.
Key to the sections of Plocoglottis
1a Plant with 1- or 2-leaved pseudobulbs ... 2
1b Plant without pseudobulbs but with slender stems carrying several to many leaves ... section Caulescentes (synonym: sect. Phyllocaulos)
2a Lip with fringed margins; lateral sepals swollen at the apex ... section Porphyrophyllos
2b Lip with entire margins; apices of lateral sepals not swollen ... section Plocoglottis