Tumbleweeds

11/13/11



dry, dead tumbleweed

      Tumbleweed or Russian thistle is an annual plant known throughout the American west.  Tumbleweeds are plants of the Salsola genus, part of the Chenopodiaceae family, that are now included in the family Amaranthaceae.  Although native to Russia, the plants grow in many parts of the world.

     Tumbleweeds were first reported in the United States in the 1870's in South Dakota, apparently imported in shipments of flax seed.  Tumbleweeds like the dry, sandy soil of deserts.  They need only a little bit of moisture and warmth to grow.




green, growing Russian thistle

      Inconspicuous flowers bloom from July through October in the junction between the leaf base and the stem and are pinkish-red and white.




Russian thistle flowers


     Leaf tips are sharply pointed to spine-tipped.  Mature plants generally grow to about three feet and are large and bushy.  The stems curve upward giving the plant an overall round shape.

Russian thistle leaf tips

     When mature in autumn, the mostly dried up Russian thistle plant breaks away from its roots, and is now called a tumbleweed.  Because it is rounded, it is rolled or tumbled by the wind.  There is a purpose to this tumbling.  A tumbleweed can produce up to 250,000 seeds, and the tumbling serves to spread those seeds.

     There are hundreds of tumbleweeds strewn across the desert floor out here where I live.  Because of their rolling motion, tumbleweeds can damage the protective soil crust, and this can lead to subsequent wind damage and topsoil loss.  Tumbleweeds can also be a fire hazard if many of the dead plants collect along fence lines, or if ignited plants blow across fire lines.

tumbleweeds along a fence line

     In moderate amounts, the immature plants are nutritious for livestock.  Phytoremediation, or the use of plants to clean up pollution, could be a possible use for tumbleweeds.  They are one of the best accumulators of uranium from the soil, and could be used to clean up soil contaminated with it.

      Tumbleweeds can also be a source of entertainment.  The song Tumbling Tumbleweeds was made popular by the Sons of Pioneers in the 1940's.