I can remember the first time I ever heard of contractile roots. It was in graduate school at the University of Maryland and a friend of mine was busy preparing a lecture on roots. He said to me something like “Did you ever notice, while pulling up dandelions, that the darn weed seems to be pulling back? As it turns out, it is!” Strange but true, dandelions, along with a diverse assemblage of other species, have contractile roots that serve to pull the plant downward. In this capacity, contractile roots go well beyond the routine function of providing anchorage for aerial portions of the plant body. For plants with certain specialized growth habits, contractile roots serve to counteract the inexorable upward growth of shoot systems in order to maintain a preferred position relative to the soil surface.
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Hayden, W. John. "Hunker Down and Hold On: Contractile Roots Give Skunk Cabbage Another Special Trait." Bulletin of the Virginia Native Plant Society 28, no. 2 (2009): 5, 8.