Self, wind and water pollination: The Hidden World of Autogamy, Anemophily, and Hydrophily
Conversations on pollination are almost always centred around bees, birds, or butterflies, but what about less common forms of pollination?
Did you know that there are self-pollinating plants? Or that wind and water can be pollinators too?
About 10 to 15 per cent of flowering plants are mainly self-pollinated, around 12 per cent of plants are wind pollinated, and only two per cent are pollinated through water. Although these methods of reproduction make up a small part of pollination as a whole, the unique part they play is no less important.
In terms of self-pollination, there are two types; autogamy and geitonogamy. The distinguishing factor between autogamy and geitonogamy is the location of male and female reproductive systems in the same flower or different flowers of the same plant. Autogamy occurs on the same flower of a plant, where the pollen grains are transferred from stamen to stigma. One example of this is Beadle’s grevillea or Grevillea beadleana, which was found to be self-compatible in a study conducted in 2002 by the University of New England. This is a flowering shrub with reddish-purplish flowers and it is endemic to the New South Wales region.
Geitonogmay occurs between different flowers of the same plant, meaning the male and female reproductive organs. Geutonogmay is common among plants which are unisexual or have male and female parts on the same plant. Spider orchids are known to perform this type of self-pollination, more specifically Grass-leafed spider orchids which only show their open bloom for a few days during their life cycle.
There are also abiotic methods of pollination, these being wind and rain. Anemophily is pollination by wind and it mainly acts as a substitute for failed self-pollination. Usually plants which use anemophily do not produce nectar and have their male and female reproductive parts on physically separate flowers. Many native Australian vegetation species have light pollen pieces which are detached from the plant in strong windy conditions. Wind as pollination works well for grasses or monocotyledonous groups, for example sedges (Cyperaceae), reeds and rushes (Juncaceae), nettles (Urticaceae), and plantains (Plantaginaceae).
As one would imagine, wind pollination can be extremely hit or miss because the plant relies on pollen grains moving in the right direction and being blown perfectly onto the correct counterpart for reproduction. Therefore, plants which rely on anemophily usually produce a large quantity of pollen because the odds of success are so low.
Hydrophily is pollination via water which usually involves floating pollen or
raft pollen. Here, the pollen is carried down a body of water, resting on the surface until it reaches an available flower stigma. Hydrophily is most common for species of seagrass but uncommon for terrestrial plants. One plant which uses water pollination is the running marsh flower, or Villarsia reniformis. This species attracts passing pollen rafts with their female flowers which rest on the surface of the water. Another aquatic plant group called Vallisneria, commonly referred to as tape or eelgrasses, uses the water to carry pollen grains released by male flowers down river to female flowers which grow up to the surface on a long stalk.
So, next time there’s a conversation surrounding pollination and people are discussing the birds and the bees, you can raise your voice in support of uncommon pollinators. They play an important and intricate part in supporting the delicate balance of the natural world.
Sources
- ➢ Hyland-Wood, Mikayla. “Guide: Promoting Our Pollinators.” Rivers of Carbon. June 2023. riversofcarbon.org.au/guide-promoting-our-p ollinators/.
- ➢ Smith JA, Gross CL. “The pollination ecology of Grevillea beadleana McGillivray, an endangered shrub from northern New South Wales, Australia.” National Library of Medicine. Jan. 1, 2002. https://www.ncbi.nlm.nih.gov/pmc/articles/P MC4233782/.
- ➢ McGillivray, D J. “Grevillea Beadleana McGill.” Flora of Australia. Feb. 24,1986. profiles.ala.org.au/opus/foa/profile/Grevillea %20beadleana.
- ➢ Watson, Phil. “Footprints in the Pollen.” Australian Plants Online, Australian Native Plants Society. July 2007. anpsa.org.au/APOL2007/nov07-1.html.
- ➢ Chookman. “Orchids of South-West Australia.” Orchids of Southwest Australia. chookman.id.au/wp_orchids/?page_id=2001 #:~:text=The%20orchid%20is%20self%20pol linating,few%20if%20any%20in%20flower.
- ➢ Candeias, Matt. “Eelgrass Sex Is Strange.” In Defense of Plants. Aug. 15, 2019. www.indefenseofplants.com/blog/tag/water+ pollination.
- ➢ Charkes, Susan. “Wind Pollination: Social Distancing in the Plant World.” Brandywine Conservancy and Museum of Art. May 5, 2020. www.brandywine.org/conservancy/blog/wind- pollination-social-distancing-plant-world#:~:te xt=By%20contrast%2C%20wind%2Dpollinat ed%20flowers,an%20enormous%20amount %20of%20pollen.-https://www.brandywine.or g/conservancy/blog/wind-pollination-social-di stancing-plant-world#:~:text=By%20contrast %2C%20wind%2Dpollinated%20flowers,an %20enormous%20amount%20of%20pollen.
- ➢ “Anemophily.” Wikipedia, Wikimedia Foundation. Apr. 28, 2024, en.wikipedia.org/wiki/Anemophily#/media/Fil e:Pine_releasing_pollen_into_the_wind_in_T untorp_1.jpg.
Author is Althea Cisneros