Intrinsic Rhythms

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Science  27 Nov 2009:
Vol. 326, Issue 5957, pp. 1164
DOI: 10.1126/science.326.5957.1164-c

Many plant species reproduce irregularly, flowering synchronously only every few years. Famous examples are the giant dipterocarp trees of Southeast Asian rainforests and the beech trees of temperate forests. Despite much research on the ecological and evolutionary aspects of this phenomenon, little is known about the proximate mechanisms by which the individual plants in a population achieve reliable synchrony in their flowering. Crone et al. addressed this question in an experimental study with a North American plant species, Astragalus scaphoides, which flowers in alternate years. By manipulating the resource budgets of individual plants (by reducing fruit set through flower removal), they showed that the levels of mobile carbohydrate control the frequency of flowering: Plants prevented from setting fruit maintained higher levels of resources and hence flowered again the next year; this resulted in pollen-limited reproduction, reducing seed set and leading to the reestablishment of synchrony the following year.

Ecol. Lett. 12, 1119 (2009).

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