High-speed pollen release in the white mulberry tree, Morus alba L
Anemophilous plants described as catapulting pollen explosively into the air have rarely attracted detailed examination. We investigated floral anthesis in a male mulberry tree with high-speed video and a force probe. The stamen was inflexed within the floral bud. Exposure to dry air initially resulted in a gradual movement of the stamen. This caused fine threads to tear at the stomium, ensuring dehiscence of the anther, and subsequently enabled the anther to slip off a restraining pistillode. The sudden release of stored elastic energy in the spring-like filament drove the stamen to straighten in less than 25 μs, and reflex the petals to velocities in excess of half the speed of sound. This is the fastest motion yet observed in biology, and approaches the theoretical physical limits for movements in plants.
© 2006 Springer. Received: 21 September 2005 / Accepted: 20 November 2005 / Published online: 8 February 2006. Supported by grants from the Southern California Environmental Health Sciences Center (NIEHS 5P30 ES07048), the Packard Foundation, Philip Morris USA Inc. and Philip Morris International. PT was supported by a Boswell Fellowship from Caltech and the Huntington Medical Research Institute. We thank MM Glovsky for early comments on the manuscript, and SD Russell and AG Miguel for provision of some specimens.
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