| MadSci Network: Botany |
Yes, floating and submerged plants can reproduce by seed if they are seed plants or by spores if they are seedless plants, such as ferns. However, many aquatic plants also reproduce asexually. Many aquatic plants are considered noxious weeds because of their rapid asexual reproduction including the floating plants, water hyacinth and water lettuce. In the floating aquatic seed plants, duckweed and water hyacinth, seeds sink. In water hyacinth, sunken seed may remain alive for 15 to 20 years and will germinate when the water level drops. Water fern (Salvinia spp.) is a floating seedless plant that mainly reproduces asexually but can also produce spores. The spores sink to overwinter but then float to the surface in the spring. Partly submerged plants usually produce their flowers above water and have aerial pollination by wind or animals. Only a few submerged aquatic plants use water pollination or hydrophily, including Elodea canadensis, eelgrass (Vallisneria spp.) and some pondweeds (Potomogeton spp.). Usually, flowers are at the water surface and pollen floats between them, termed epihydrophily. Vallisneria is unusual because the tiny male flowers detach from the plant and float to the surface. They float to the female flowers and anthers contact the stigmas to transfer the pollen. Underwater cross-pollination or hypohydrophily, is very rare but occurs in northern water-starwort (Callitriche hermaphroditica) and almost all seagrasses, such as Zostera spp. Underwater pollination is also called submarine pollination. Seagrasses are submerged aquatic seed plants that live in seawater. In species with underwater pollination, seeds germinate underwater. See the references for additional details, or search google.com to find numerous webpages on aquatic plants. Search google scholar to find scientific articles. References Flowering and Dormancy in Duckweeds Water hyacinth (Eichornia crassipes) Water Lettuce (Pistia stratiotes) Water fern Azolla mexicana Argue, Charles L. 1992. Water Pollination in Minnesota Plants. Minnesota Plant Press 11(3) Eel Grass (Vallisneria spp.) C. Thomas Philbrick. 1993. Underwater Cross-Pollination in Callitriche hermaphroditica (Callitrichaceae): Evidence from Random Amplified Polymorphic DNA Markers. American Journal of Botany 80: 391-394. Ackerman, J.D. 1997. Submarine pollination in the marine angiosperm Zostera marina (Zosteraceae). II. Pollen transport in flow fields and capture by stigmas. American Journal of Botany 84: 1110-1119. J. M. Pettitt, C. A. McConchie, S. C. Ducker & R. B. Knox. 1980. Unique adaptations for submarine pollination in seagrasses. Nature 286: 487-489 doi:10.1038/286487a0
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