Dendrobium (den-DROH-bee-um) is a huge genus of orchids. It was established by Olof Swartz in 1799 and today contains about 1,200 species. The genus occurs in diverse habitats throughout much of south, east and southeast Asia, including the Philippines, Borneo, Australia, New Guinea, Solomon Islands and New Zealand. The name is from the Greek dendron ("tree") and bios ("life"); it means "one who lives on trees", or, essentially, "epiphyte".
In 1981, Briegar reclassified all terete-leaved Dendrobiums from Australia and New Guinea into a new genus, Dockrillia. The Winika orchid from New Zealand was formerly D. cunninghamii, but has now been moved into a monotypic genus Winika. In 1989, Clements upgraded the D. speciosum complex into individual species; similarly, the D. bigibbum complex (which contains the well-known Cooktown Orchid of Australia, D. phalaenopsis) has recently been split up.
Dendrobium species are either epiphytic, or occasionally lithophytic. They have adapted to a wide variety of habitats, from the high altitudes in the Himalayan mountains to lowland tropical forests and even to the dry climate of the Australian desert.
This genus of sympodial orchids develop pseudobulbs, which vary in length from a few centimetres (e.g. Dendrobium cuthbertsonii) to two metres long (e.g. Dendrobium pulchellum). Most grow into long reedlike stems. Some appear densely covered with short white or black hairs (Dendrobium infundibulum).
In selected species, the short, ovate leaves grow alternately over the whole length of the stems, in others, the leaves are bunched towards the apex of the stem (e.g. Dendrobium tetragonum). The axillary inflorescence vary in length from insignificant to 1m long, and can carry from a few (1-4) (e.g. Dendrobium nobile) to as many as 100 (e.g. Dendrobium speciosum) flowers. Deciduous species carry their leaves for one to two years then typically flower on leafless canes, while canes of evergreen species usually flower in the second year and can continue to flower for a number of years (e.g. Dendrobium densiflorum).
These orchids grow quickly throughout summer, but take a rest during winter. Dormant buds erupt into shoots from the base of the pseudobulb mainly in spring, and a few species in autumn. This is then followed by rapid growth of new roots. Reproduction is usually through seed, but a few species reproduce asexually through keikis produced along the stem, usually after flowering and sometimes as a result of injury to the growing tip. [by Wikipedia]
Dendrobium is a diverse genus of orchids with different cultural needs. Many go through a growth phase and then a rest phase during the course of one year, and must be given water and temperature to match these periods of growth and rest. Flowers can last one day to many weeks, depending on the type. Owing to the extreme diversity of the genus, we have categorized culture according to the following main types [by: The American Orchid Society]: