WHAT has no legs, lives in the forest and accelerates with a g-force 800times greater than a rocket taking off? It鈥檚 the stamen of the bunchberry dogwood (Cornus canadensis), a ground-covering plant with a pollen-dispersion system now crowned the fastest mover of the plant world.
To record the flower鈥檚 explosive pollen propulsion, Joan Edwards at Williams College in Williamstown, Massachusetts, had to use digital recording equipment designed to film car-crash tests at 100,000 frames per second. 鈥淚t鈥檚 truly amazing to watch, and so beautiful,鈥� says Edwards. 鈥淲ith an acceleration of 24,000 metres per second per second, it鈥檚 much faster than many animal movements.鈥�
The two-stage firing mechanism operates like a medieval trebuchet catapult. As the white petals of the tiny flower, which measures just 2 millimetres across, first open, they trigger the release of four stamens that shoot straight up, flicking the pollen up and away from the flower (Nature, vol 435, p 164).
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This powerful system operates through changes in the turgidity of the cells, and so costs the plant little energy. Edwards believes that it evolved to ensure pollen transfer by the most effective insect carriers. For example bumble bees can trigger the mechanism, which will embed pollen into hairs on their backs. The low-growing plants can also use the wind as a back-up delivery system.
