A tumbleweed is the above-ground part of a plant that, once mature and dry, separates from the root and tumbles (rolls) away in the wind. Usually, the tumbleweed is the entire plant apart from the roots, but in a few species it is a flower cluster.[1] The tumbleweed habit is most common in steppe and desert plants. The tumbleweed is a diaspore, aiding in dispersal of propagules (seeds or spores). It does this by scattering the propagules either as it tumbles, or after it has come to rest in a wet location.[2] In the latter case, the tumbleweed opens mechanically as it absorbs water; apart from its propagules, the tumbleweed is dead.
Posted on Sunday, 27 September 2009
