Friday, September 9, 2016

King Orchids
Dendrobium speciosum var. hillii
(Thelychiton tarberi)

It’s king orchid time again, and these lovely plants are in flower in gardens, and in the wild.
Like all our native orchids, these are tough plants. You can see that this orchid is thriving in its very exposed situation, high on a tree in a degraded environment, where most of the original sheltering forest has disappeared.

It may have trouble making babies up there in its rather isolated site, though. First, it has to be found by pollinators, such as the stingless bee Tetragonula carbonaria. The chances are better when there are quite a lot of the orchids around top attract them, but it’s all a bit sad for the bees. Like most orchids, these lovely plants are “con artists”, attracting insects to do the hard work of transferring the pollen to other flowers, by promising nectar rewards with their shape, colour, and perfume – but not actually making the effort to produce any nectar. Working without pay is not fair in anyone’s book!
However, despite its fine show, this plant may be wasting its fragrance on the air. If no bee finds it, it will never produce seed, a continuing problem it shares with many of our native plants as our bushland is ever more segmented and it gets harder for the increasingly isolated plants to attract pollinators.

Unlike some of their closest relatives, king orchids are tree-dwelling plants. Their fine seeds are happy to germinate on the rough park of perfectly straight trees like the one below. All they need is for the right kind of fungus to be already there, to help the helpless little seeds to begin growing.

And orchid seeds are unusually helpless, which means they must become parasites from birth. Most parent plants provide their seeds with a little food package (endosperm) to feed the newly germinating baby plant. Orchids, in their enthusiasm for producing enormous numbers of their very tiny seeds, neglect this rather basic precaution. If none of their seeds can latch onto a suitable fungus nursemaid to provide them with the necessary nutrients, then the orchid’s efforts to create a new generation will fail.
Orchids are one of the most successful plant families in the world, proving that, all things being equal, it pays to be a user. All is not equal in our local environment, however, and our district’s once-rich orchid flora is dwindling away.
All praise to those who give it a chance to recover, by conserving and restoring patches of our local bushland.