They are generally considered to be a nuisance, and occasionally become hazardous. Tumbleweeds are commonly seen in arid sites in the West and they become dominant in overgrazed sites. Initially, the dry plant has about 2,500 seeds, but seeds are scattered as the desiccated weed rolls and bounces along. When the wind catches the light globe of stems, it sends the entire plant - including stems, prickles and seeds - rolling and bouncing across the landscape. Our tumbleweeds are annuals, growing from a seed to round globe 3 to 5 feet tall in a single year.Īs the seeds mature, the entire aboveground portion dries out and breaks from the root at the soil surface. Tumbleweed is also a term referring to a seed dispersal system, employed by multiple groups of unrelated species. Most tumbleweeds are diploids, with two copies of each chromosome, but recently triploid (three copies), tetraploid (four copies) and hexaploid (six copies) lineages have been discovered. tragus in California, indicating that Russian thistles were introduced multiple times, from different places.įurthermore, other unidentified - meaning they have no official names yet - species have been found. In addition, molecular studies have identified two distinct genetic forms of S. But currently seven species of Salsola are in North America, none are native and all are referred to as tumbleweeds. The most familiar and probably the most common in the West is Russian thistle, Salsola tragus, the first introduced. Tumbleweeds are a group, not a single species. Russian thistle, also known as tumbleweed, growing on the bank of the Paria River in Utah.
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