Orchid Information - Genus Dendrobium section Cadetia

Dendrobium section Cadetia forms a very distinctive and natural group of species. They are small plants with one-leaved slender stems or small swollen pseudobulbs. The short, one-flowered inflorescences arise from the apex of the stem in the axil of the leaf. In subsection Sarcocadetia an additional inflorescence arises from a point just below the apex of the stem on the abaxial side of the leaf. Most species have pure white flowers, including the not very aptly named C. citrina (Ridl.) Schuit., which has the largest flowers in the section, up to 2.5 cm across. The Australian C. taylorii (subsection Cadetia; wrongly included in subsection Pterocadetia by Morris et al.) is fairly widespread in amateur collections, but the New Guinea taxa are not less worthy of attention by the lover of miniature orchids. Cadetias are generally easily cultivated, but they dislike being constantly wet at the roots, while on the other hand they should not be allowed to dry out too much. Species occurring at very high elevations, above 2500 m, have proved to be rather more difficult to keep in cultivation.

Systematics
Dendrobium section Cadetia can be divided into three subsections, based on the position of the inflorescences and the shape of the cross-section of ovary and stem:

Subsection Cadetia
Inflorescences arising only from the leaf-axil, their base enveloped by a persistent, folded scale-leaf ('spathe'); ovary round in cross-section, usually densely covered with papillae or soft spine-like hairs; stems almost round to weakly 4-angled in cross-section, with rounded angles.

Subsection Pterocadetia
Inflorescences arising only from the leaf-axil, their base enveloped by a spathe; ovary triangular to almost V-shaped in cross-section or 6-ribbed, glabrous; stems usually sharply 4-angled in cross-section, with concave sides, often almost 4-winged.

Subsection Sarcocadetia
Inflorescences arising from the leaf-axil and also from a point just below the stem apex on the abaxial side of the leaf, their base enveloped in a scarious tubular sheath and only in some species in addition by a spathe; ovary 6-winged to triangular to almost V-shaped in cross-section, glabrous; stems almost round to weakly 4-angled in cross-section, with rounded angles.

While the names of the two last-mentioned subsections were originally proposed by Schlechter (1911-1914), the circumscription of the subsections is modified here. As a result, many species included by Schlechter in subsection Pterocadetia (e.g. Cadetia chionantha) are now assigned to subsection Sarcocadetia. This somewhat unfortunate situation is a consequence of the typification of the sections by van Royen (1979).

In New Guinea Dendrobium section Cadetia contains the following 51 species:

Dendrobium albiflorum
Dendrobium apiculiferum
Dendrobium aprinoides
Dendrobium aprinum
Dendrobium arfakense
Dendrobium bialatum
Dendrobium cadetia
Dendrobium ceratostyloides
Dendrobium chamaephytum
Dendrobium chionanthum
Dendrobium crassula
Dendrobium cuneilabium
Dendrobium cyclopense
Dendrobium danipense
Dendrobium doormanii
Dendrobium echinocarpum
Dendrobium fluctuosum
Dendrobium fruticosum
Dendrobium funiforme
Dendrobium goliathense
Dendrobium heteroideum
Dendrobium karoense
Dendrobium kempfianum
Dendrobium lactiflorum
Dendrobium lacorum
Dendrobium latoureoides
Dendrobium ledifolium
Dendrobium legareiense
Dendrobium macrolobum
Dendrobium micronephelium
Dendrobium mulderi
Dendrobium obreniforme
Dendrobium platylobum
Dendrobium pseudoaprinum
Dendrobium praemorsum
Dendrobium quinquelobum
Dendrobium recurvatum
Dendrobium reflexum
Dendrobium remotisepalum
Dendrobium repandum
Dendrobium rumphiae
Dendrobium sayeri
Dendrobium schuitemanii
Dendrobium simile
Dendrobium similissimum
Dendrobium stenocentrum
Dendrobium subfalcatum
Dendrobium subradiatum
Dendrobium takadui
Dendrobium transversilobum
Dendrobium triquetrum
Dendrobium umbellatum
Dendrobium versteegii