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Reproductive Biology of Selected Aquatic Plants
Robert R. Haynes
Annals of the Missouri Botanical Garden
Vol. 75, No. 3 (1988), pp. 805-810
Published by: Missouri Botanical Garden Press
Stable URL: http://www.jstor.org/stable/2399368
Page Count: 6
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Aquatic weeds are species that inhabit bodies of water in such quantities that they either interfere with man's usage or become a health hazard by serving as a breeding area for insects, especially mosquitoes. These plants are most often introduced species. They increase in numbers mostly by vegetative reproduction, including stem or leaf fragmentation, budding, or turion formation. For dioecious species in which only one sex occurs in an area, vegetative means are the only methods of reproduction. Monoecious species or species with perfect flowers often produce viable seeds, which usually are not important for increasing the population size, as they are deposited in large mats and do not get enough light or other requirements for germination. Some species that reproduce sexually, such as Eichhornia azurea, are self-sterile, but others, such as Eichhornia crassipes or Ottelia alismoides, are self-compatible. Ottelia alismoides, in fact, almost always is self-pollinated. Before the flowers open, the pollen tubes grow to the stigma from the anther. The flower eventually opens, but fertilization has already occurred. Pollination may be by insects (e.g., Hydrocharis morsus-ranae) or by wind (Potamogeton nodosus); or it takes place at the surface of water by contact between stigma and anther (Lagarosiphon), by airborne pollen (Hydrilla verticillata), or by water-borne pollen (Elodea canadensis); or pollination may occur underwater (Najas minor).
Annals of the Missouri Botanical Garden © 1988 Missouri Botanical Garden Press