Tuesday, 12 October 2010
Dutchman's Pipe a reasonable outcome of natural selection*
*Another from the archive - talked about on radio but not blogged. I love this plant and its story, and enjoy seeing the variety of different Artistolochia (and Pararistolochia) flowers in glasshouses around the world. In 2006 I said (a little more succintly than I do today I notice):
In Richard Dawkins’ spirited defence of atheism, The God Delusion, he cites the Dutchman’s Pipe (Aristolochia trilobata) as an improbable result of chance, but a reasonable outcome of natural selection.
What makes this plant, and indeed all species of Aristolochia, worthy of such lofty contemplation is the intricate relationship between the flower and its insect companions.
Like the giant Titan Arum, the flowers smell like rotting flesh. And like the arum, they attract flies. The Dutchman’s Pipe, however, has an extra trick up its sleeve.
The inside of the flower is covered in stiff hairs that capture the insect unless it leaves a load of pollen. The hairs then relax and the insect receives a fresh dose of pollen to take to the next Dutchman’s Pipe.
In Australia we have close relatives of Aristolochia, once included in the same genus but now called Pararistolochia (i.e. a bit like Aristolochia).
The Australian species are an important, but declining, food source for the larvae of the large birdwing butterflies. In their place, the weedy Dutchman’s Pipe from Brazil attracts the same butterflies but the larvae are poisoned by the unexpected toxins.
Whether native or exotic, all species contain a potent mix of often toxic chemicals. Some have been confused with traditional medicinal plants, leading to the ingestion of 'aristolochic acids' which have been linked to severe kidney damage or urinary tract cancer.
In the Pyramid end of the Tropical Centre at the Royal Botanic Gardens (the safe place to grow and view them), we have two species twining there way towards the glasshouse roof. The Pararistolochia from far north Queensland, with small flowers but still with the characteristic ‘pipe’ swelling at the base, flower in early December in 2006.
Image: A native Dutchman’s Pipe from far north Queensland, growing in the 'Pyramid'.