Genus Dendrobium

Dendrobium Sw.,
Nova Acta Regiae Soc. Sci. Upsal. 6 (1799) 82.

Very small to large sympodial epiphytic or terrestrial plants, with or without elongated rhizomes. Pseudobulbs present or absent, when present consisting of one to many internodes, short and thick to much elongated and slender, with one to many leaves; when absent stem elongated, slender, not fleshy, many-leaved. Leaves arranged in two rows, sheathing at the base or not, sheath sometimes hairy (hairs either blackish or white, not yellow or red-brown as in the genus Trichotosia), blade very rarely hairy, sometimes terete or laterally compressed, almost always deciduous, duplicate, leathery or sometimes stiffly thin-textured. Inflorescence lateral from the upper part of the stem, or terminal, a raceme or carrying a single flower. Flowers very small to large, resupinate or not, long-lived or ephemeral, often showy. Dorsal sepal almost always free from the lateral sepals, which are usually connate at the base, forming a distinct mentum (sometimes resembling a spur). Petals extremely variable, often fairly similar to the dorsal sepal, but in many species (e.g. most species of section Spatulata) widely different in size and shape. Lip without spur, usually not mobile. Column-foot present, usually longer than the column proper. Pollinia 4, solid, caudicles absent, stipe absent, viscidium absent.

Sri Lanka, tropical continental Asia, Taiwan, Japan, Malaysia, Singapore, Brunei, the Philippines, Indonesia, Papua New Guinea, Australia, New Zealand, Pacific islands, east to Tahiti. About 900 species; in New Guinea c. 350 species.

Epiphytes in lowland and montane forest. Some species are terrestrial in swampy places with sparse vegetation, in subalpine grassland, or on road banks, others grow on rocks and cliffs, but of the latter category most can also be found as epiphytes.

From a horticultural point of view Dendrobium is by far the most important orchid genus in New Guinea. Next to Bulbophyllum it is also one of the largest. It is divided into more than 40 sections, of which 22 occur in New Guinea. In New Guinea the showy species belong predominantly to the sections Latouria (e.g. Dendrobium alexandrae Schltr. ALEXA278.JPG ), Spatulata (e.g. Dendrobium lasianthera J.J.Sm. LASIA12.JPG ), Phalaenanthe (Dendrobium bigibbum Lindl. BIGIB70.JPG )and Pedilonum (e.g. Dendrobium smillieae F.Muell. SMILL313.JPG , Dendrobium lawesii F.Muell. LAWES508.JPG , and Dendrobium cuthbertsonii F.Muell. CUTHB538.JPG ). The countless millions of dendrobiums produced by the cut flower industry in Thailand and Singapore, adorning every hotel and restaurant in Southeast Asia, are hybrids of species originating from New Guinea and Australia, belonging to sections Phalaenanthe and Spatulata.

Most of the sections of Dendrobium are quite distinct. Regrettably, the popular sections Calyptrochilus and Oxyglossum, which contain several of the most charming orchids of New Guinea, have proved to be exceptions to this rule; we had to conclude that they can not be separated in a consistent way from section Pedilonum. Moreover, during the preparations for the current CD-ROM it was found that several sectional names in current use are synonyms of older, previously discarded names. As a result, some sections have changed names compared with Volume I of this series.

The following 22 sections are known to occur in New Guinea (between brackets the name as used in Vol. I, or the name in general use):

Brevisaccata (Trachyrhizum)
Crumenata (Rhopalanthe)
Distichophyllae (Distichophyllum)
Fugacia (Euphlebium)
Pedilonum (including Calyptrochilus, Oxyglossum, Cuthbertsonia)
Phalaenanthe (Bigibba)
Rhizobium (genus Dockrillia)