The genus Dendrobium belongs to the family Orchidaceae and consists of around 900 species. They are found in the Pacific Islands, Australia, New Guinea and Southeast Asia. There are 50 to 60 species native to Australia with a huge variety within the species with almost all colours and combinations represented. Blooms may last for a few hours or for days. Dendrobiums have a range of requirements under cultivation, depending on the species.
They are mostly epiphytes or lithophytes. In the wild epiphytes grow on the branches or trunk of a tree but well above the ground. They are not parasites but utilise the dead bark and leaf litter of the host plant. Lithophytes differ in that they habitually grow on rocks, virtually without soil. Many epiphytes are also capable of growing as lithophytes.
Dendrobium bigibbum or Cooktown Orchid is native to northern Queensland and common on Cape York Peninsula. It is a clump-forming epiphyte which may also grow as a lithophyte. It has striking sprays of up to 20 spectacular magenta, mauve, lilac or white flowers. The flowering season is mainly from March to July. It likes warm conditions and needs to be kept dry during winter when it is dormant. This species is the flower emblem of Queensland.
Dendrobium falcorostrum or Beech Orchid is native to Queensland and New South Wales. It produces racemes of highly fragrant, white to cream flowers from August to November. It is very popular in cultivation, and grows well as an epiphyte or in a container.
The Pink Rock Orchid is found from Newcastle in New South Wales north to Rockhampton in Queensland. It is very commonly cultivated and grows well as an epiphyte or as a container plant. The flowers are generally pink but white and purple flowers in various combinations are also produced. Flowering is mainly from August to November. As the name suggests, it is a lithophytic species, compact in form and produces up to twelve fragrant flowers on each spike. There are some very nice cultivars originating from this species.
Dendrobium tetragonum or Tree Spider-orchid is native from northern Queensland south to central New South Wales. It produces very fragrant racemes of spider-like, green to yellowish flowers with reddish-purple markings. Flowers are produced mainly from May to October. It is an epiphytic species popular in cultivation but can be slow to establish after division or other disturbance.
One of the more unusual dendrobiums is Dendrobium canaliculatum or onion orchid which is native to northern Queensland and usually epiphytic. It has unique scaly pseudobulbs from which it gets its common name. In spring it produces up to 40 narrow twisted flowers which are white with yellow to brown tips and white and purple labellum. It likes warmth and bright light and needs to be kept dry in winter.
There are now many Australia native dendrobium hybrids available. These are very popular, relatively fast-growing and make a delightful addition to any garden.