Hybridized Tumbleweed Species Rapidly Expanding Range in California

Posted on May 5, 2016

A new species of tumbleweed was discovered in California in 2002. The hybridized species, Salsola ryanii, was created from two invasive species of tumbleweed. Earlier studies found this new tumbleweed was not likely to become invasive. The new research indicates those studies were wrong.

University of California, Riverside researchers believe Salsola ryanii is likely to become an important invasive species that could spread beyond California to other states. It has dramatically expanded its geographic range in California in just a decade.

Salsola ryanii is described as an allopolyploid. This means it is an organism with two or more complete sets of chromosomes derived from different species. It is a hybridization between two other invasive tumbleweed species: Salsola tragus and Salsola australis.

The researchers gives two reasons for the rapid expansion of the Salsola ryanii tumbleweed. One is the dispersal of seeds from individual plants due in large part to the "tumbling" phenomenon. The other reason is there are multiple independent hybridizations of the two original tumbleweed species. A research paper on the invasive weed was published here in the American Journal of Botany.

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