Tuesday, April 15, 2014

Myrmecochory - Ants in Our Plants

Bloodroot seeds with elaisomes 
     An interesting symbiotic relationship exists where approximately 5% of the world's plants have evolved specialized seed attachments that attract certain species of ants to disperse their seeds. About 11, 000 species of plants grow these specialized fleshy structures, rich in lipids and proteins (and sometimes producing ant attracting pheromones) called elaisomes. The ants usually take the seeds back to their nests where the elaisome is consumed but the seeds are discarded, often inside the nests' nutrient rich waste dumps where they are protected from predators (or fires) and finds it easier to germinate. This goes by the name of myrmecochory.
     Our region is especially rich in these species of myrmecochorous plants, with approximately 30% of our spring wildflowers having evolved this way. This occurs in over 90 species in 25 families in the DC area, although not all of them are native. A partial list of plants includes: Trilliums, Hepaticas, Spring Beauties, Woodrushes, Troutlilies, Corydalis, Dutchman's Breeches, Squirrel Corn, Wild Bleeding Hearts, Twinleaf, Rue Anemone, Wild Licorice, Trailing Arbutus, Bloodroot, Wild Ginger, Greater Celandine, most Violets, Pansies, Speedwells, Snowdrops, Daffodils, Grape Hyacinths, Star-of-Bethlehem, Ground Ivy, Henbit, Deadnettle, some Iris, Sedges, Spurges, Bellworts, perhaps Bluebells (though I think they're really water dispersed) , and unfortunately some invasive Thistles and Knapweeds.
     So the next time you see some ants at your picnic or while out hiking, remember that they may be the reason you get to enjoy the spring wildflowers as well.

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