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Dendrobium tetragonum

(Tree Spider Orchid)

One of the most curious local epiphytic orchids, the tree spider orchid has long, pendulous, four-sided canes (pseudobulbs) with wiry bases, and dramatic flowers about 40mm across. It seems to be a delicate orchid, growing invariably on the south side of large trees - sometimes quite high up (e.g. 10-15 metres up) - in heavy shade. It is very showy in flower.


This plant was photographed by while out on a local walk to reconnoitre some clear-felling many years ago. Last time I looked this plant was still alive but many other orchids and epiphytes were illegally extracted and sold or killed in the subsequent logging.

As with many of the epiphytic orchids, these elaborate flowers attract tiny insects which are its pollinators. I don't know if the tree spider orchid uses native bees, some small gnats, or something similar. The plants flower in spring as with most of the orchids here and the flowers are very long-lasting, holding their colour and shape for about a month.

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