Botany: A record-breaking pollen catapult
The release of stored elastic energy often drives rapid movements in animal systems1, 2, and plant components employing this mechanism should be able to move with similar speed. Here we describe how the flower stamens of the bunchberry dogwood (Cornus canadensis) rely on this principle to catapult pollen into the air as the flower opens explosively3, 4, 5. Our high-speed video observations show that the flower opens in less than 0.5 ms — to our knowledge, the fastest movement so far recorded in a plant. Cornus canadensis grows in dense carpets in the vast spruce-fir forests of the North American taiga. As bunchberry flowers burst open, their petals rapidly separate and flip back to release the stamens (Fig. 1). During the first 0.3 ms, the stamens accelerate at up to 24,000plusminus6,000 m s-2 (2,400g), reaching the high speed (3.1plusminus0.5 m s-1) necessary to propel pollen, which is light and rapidly decelerated by air resistance (terminal velocity, 0.12plusminus0.03 m s-1 (meanplusminuss.e.m.); n=7). The pollen granules are launched to an impressive height of 2.5 cm (range, 2.2–2.7 cm; n=5), which is more than ten times the height of the flower: from this height, they can be carried away by the wind. (For methods and movies, see supplementary information.)
Edwards, Joan, Dwight Whitaker, Sarah Klionsky, and Marta J. Laskowski. 2005. "Botany: A record-breaking pollen catapult." Nature 435(7039): 164.
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