Hydrophily

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Vallisneria spiralis is an example of hydrophily. Female flowers reach the water's surface temporarily to ensure pollination. Vallisneria spiralis Erasmus Darwin 1789.jpg
Vallisneria spiralis is an example of hydrophily. Female flowers reach the water's surface temporarily to ensure pollination.

Hydrophily is a fairly uncommon form of pollination whereby pollen is distributed by the flow of waters, particularly in rivers and streams. Hydrophilous species fall into two categories: (i) Those that distribute their pollen to the surface of water. e.g. Vallisneria's male flower or pollen grain are released on the surface of water, which are passively carried away by water currents; some of them eventually reach the female flower (ii) Those that distribute it beneath the surface. e.g. seagrasses in which female flower remain submergered in water and pollen grains are released inside the water.

Contents

Surface pollination

Surface pollination is more frequent, [1] and appears to be a transitional phase between wind pollination and true hydrophily. In these the pollen floats on the surface and reaches the stigmas of the female flowers as in Hydrilla , Callitriche , Ruppia , Zostera , Elodea . In Vallisneria the male flowers become detached and float on the surface of the water; the anthers are thus brought in contact with the stigmas of the female flowers. [1] Surface hydrophily has been observed in several species of Potamogeton as well as some marine species. [2]

Submerged pollination

Species exhibiting true submerged hydrophily include Najas , where the pollen grains are heavier than water, and sinking down are caught by the stigmas of the extremely simple female flowers, [1] Posidonia australis or Zostera marina [3] and Hydrilla.

Evolution

Hydrophily is unique to obligate submersed aquatic angiosperms with sexually reproductive parts completely submerged below the water surface. Hydrophily is the adaptive evolution of completely submersed angiosperms to aquatic habitats. True hydrophily occurs in 18 submersed angiosperm genera, which is associated with an unusually high incidence of unisexual flowers. [4]

Related Research Articles

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<span class="mw-page-title-main">Pollen</span> Grains containing the male gametophytes of seed plants

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<span class="mw-page-title-main">Aquatic plant</span> Plant that has adapted to living in an aquatic environment

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<span class="mw-page-title-main">Pollination</span> Biological process occurring in plants

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<span class="mw-page-title-main">Hydrocharitaceae</span> Family of aquatic plants

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<span class="mw-page-title-main">Anemophily</span> Wind pollination

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<i>Potamogeton diversifolius</i> Species of aquatic plant

Potamogeton diversifolius is a species of aquatic plant known by the common names waterthread pondweed and diverse-leaved pondweed. It is native to most of the United States, as well as sections of southwestern Canada, and northern Mexico, where it grows in water bodies such as ponds, lakes, ditches, and slow-moving streams. This is a perennial herb producing a very narrow, compressed stem branching to a maximum length around 35 centimeters. It has thin, pointed linear leaves a few centimeters long spirally arranged about the thin stem. The inflorescence is a small spike of flowers emerging from the water surface. Inflorescences also grow on submersed sections of the stem; these are smaller and spherical. It can be difficult to distinguish from similar species of pondweed.

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<span class="mw-page-title-main">Monocotyledon reproduction</span>

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<span class="mw-page-title-main">Pollination of orchids</span>

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References

  1. 1 2 3 Chisholm 1911 , p. 3
  2. Zhang, Xiao-lin; Gituru, Robert W.; Yang, Chun-feng; Guo, You-hao (2010). "Exposure to water increased pollen longevity of pondweed (Potamogeton spp.) indicates different mechanisms ensuring pollination success of angiosperms in aquatic habitat". Evolutionary Ecology. 24 (4): 939–953. doi:10.1007/s10682-010-9351-z. ISSN   0269-7653. S2CID   1512192.
  3. Cox 1988, pp. 261–279.
  4. Du, Z.-Y., Wang, Q.-F. (19 December 2014). "Correlations of Life Form, Pollination Mode and Sexual System in Aquatic Angiosperms". PLOS ONE. Public Library of Science. 9 (12): e115653. doi: 10.1371/journal.pone.0115653 . ISSN   1932-6203. PMC   4272260 . PMID   25525810. CC-BY icon.svg Text was copied from this source, which is available under a Creative Commons Attribution 4.0 International License.

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