Friday, 26 March 2010

The Flowering Bluetongue*



With more than 20,000 species of flowering plants in Australia it’s not surprising to discover a plant you haven’t heard of before. With each new plant comes a new story of how it lives and reproduces in its particular habitat.

Today we’ll look at a plant that sounds like it should be an animal, the Blue Tongue. It’s also sometimes called the Native Lasiandra which tells you more about what kind of plant it is.
Lasiandra is the name we used to give to Tibouchina, the vivid blue and purple (or even pink) flowering trees and shrubs grown widely in Sydney but native to South America.

This native Australian plant (Melastoma affine) grows in the tropics and extends up through into India. It comes down as far south as Kempsey in New South Wales.

Like the Tibouchina, the flowers are large and showy. They last only a few days but the plant keeps producing more, sometimes for many months or even year-round. It needs full sun and plenty of water to grow and flower well.

The other common name, Blue Tongue, refers to the colour of your tongue if you eat the fruit. And yes, Simon, you can eat this one. Apparently it tastes good but the dark blue discolouration to your mouth puts many people off eating it.

The flowers are pollinated in the wild by carpenter bees – the Giant Carpenter Bee and the Metallic Green Carpenter Bee. The carpenter bees grab hold of the stamen (the bit that holds the pollen) and give it a good shake.

Introduced Honey Bees can’t ‘buzz pollinate’ – they don’t have the ability or technique to vibrate their wings while clasping the stamen. So they can only gather pollen if it has been already released onto the petals. Because they collect and store it quite deliberately, they don’t get covered in pollen and so don’t cross-pollinate the flowers like the carpenter bees.

We grow the Blue Tongue at Mount Annan Botanic Garden, in the Fruit Loop display behind the shop and restaurant, or you can see it here in the Royal Botanic Gardens off the path heading from Lion Gate Lodge towards the point.

Image: A Bluetongue (flower) at Mount Annan Botanic Garden

*This Passion for Plants posting will also appear on the ABC Sydney website (possibly under 'gardening'), and is the gist of my 702AM radio interview with Simon Marnie on Saturday morning, between 9-10 am.

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