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'.

2 comments:

Anything Australian said...

My first encounter with the Dutchmans pipe was amazement at the interesting shaped flowers dangling from the vine located at May Gibbs home (Nucote), Neutral Bay. The piped shaped flowers have intricate patterns on the petals when the flower opens. The Dutchmans pipe vine appeared to be a vigorous growing plant similar to the passionflower. I decided to do some research on the internet when I got home and discovered the plant (Dutchman’s Pipe Aristolochia elegans)unfortunately has a negative side of being poisonous to the caterpillars of the Richmond Birdwing Butterfly. If the butterfly lays its eggs on the leaves mistaking it for the host plant sadly the caterpillars will not survive because the leaves are poisonous. If anyone is interested the plant is still in flower at May Gibbs home, Nutcote at Neutral Bay. I was given some seed pods on the day but will not be planting them in my garden.

Tim Entwisle said...

Thanks for more background on the weedy species - I mention this in passing but good to stress! It's a wonderful plant and such as shame it is competing with native species in more tropical areas.