Department of Geography and Environmental Engineering, Ames Hall, 3400 N. Charles Street, Johns Hopkins University, Baltimore, Maryland 21218 USA.
Am J Bot. 2009 Sep;96(9):1703-11. doi: 10.3732/ajb.0800407.
Pollen dispersal is a fundamental aspect of plant reproductive biology that maintains connectivity between spatially separated populations. Pollen clumping, a characteristic feature of insect-pollinated plants, is generally assumed to be a detriment to wind pollination because clumps disperse shorter distances than do solitary pollen grains. Yet pollen clumps have been observed in dispersion studies of some widely distributed wind-pollinated species. We used Ambrosia artemisiifolia (common ragweed; Asteraceae), a successful invasive angiosperm, to investigate the effect of clumping on wind dispersal of pollen under natural conditions in a large field. Results of simultaneous measurements of clump size both in pollen shedding from male flowers and airborne pollen being dispersed in the atmosphere are combined with a transport model to show that rather than being detrimental, clumps may actually be advantageous for wind pollination. Initial clumps can pollinate the parent population, while smaller clumps that arise from breakup of larger clumps can cross-pollinate distant populations.
花粉传播是植物生殖生物学的一个基本方面，它维持着空间上分离的种群之间的连通性。花粉结块是虫媒授粉植物的一个特征，通常被认为不利于风授粉，因为结块比单个花粉粒传播的距离更短。然而，在一些分布广泛的风授粉物种的扩散研究中已经观察到花粉结块。我们使用 Ambrosia artemisiifolia（豚草；菊科），一种成功的入侵被子植物，在一个大的野外环境中，研究结块对花粉在自然条件下风传播的影响。在雄性花散粉过程中以及在大气中传播的空气中同时测量结块大小的结果与运输模型相结合，表明结块实际上可能有利于风授粉，而不是有害的。最初的结块可以给母种群授粉，而从较大结块中产生的较小结块可以异花授粉到较远的种群。
