Dendrobium section Rhizobium: An Update on breeding, ANOS Award Standards and Culture
Introduction to Dendrobium section Rhizobium
Dendrobium sect. Rhizobium Lindl. was established by John Lindley in 1851 based on Den. linguiforme. This classification was used by Schlechter in his major revision of Dendrobium in 1911-14. Brieger proposed in 1981 that this group be separated as a new genus Dockrillia, but this was rejected. Section Rhizobium includes around 30 species, which are mainly centered in Australia (17 –18 species) and Papua New Guinea (10 species so far described), with others in New Caledonia, Fiji, Tahiti, Samoa, Aru Islands and Vanuatu. Like so many orchids, name changes have been common over the years – for example Den. striolatum Rchb.f. was described as Den. teretifolium (1839), Den. milliganii (1859) and Callista striolata (1891) (Clements 1989).
The species are very variable in leaf form and flowers, which are commonly non-resupinate, appearing upside down. Each growth typically carries only a single leaf, which in the majority of species is long, pendulous, and terete. Some such as Den. linguiform
e deviates from other species by having broad, laterally flattened leaves, which are very fleashy and