Submitted to: Western Society of Weed Science Meeting Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: December 31, 2008
Publication Date: N/A
Technical Abstract: Russian thistle or tumbleweed is a common alien weed in many parts of the western USA. However, the taxonomy of this weed has been very confusing. Recent studies of plants found in California using morphological and molecular genetic characters have revealed the existence of at least five distinct species. Salsola tragus, is the most common and widespread tumbleweed. Salsola australis occurs primarily in California, Arizona and Mexico and also occurs in South Africa and Australia, and surprisingly may be native to the latter continent. Salsola ryanii appears to be an allopolyploid derivation involving tetraploid S. tragus and diploid S. australis. Salsola paulsenii Litv. occurs in dry sandy desert conditions. Salsola x gobicola appears to be a derivative of hybridization between S. tragus and S. paulsenii. Other Salsola species occurring in N. America include S. collina, which occurs east of the Sierra and Rocky Mountains; S. kali, which is restricted to east and south coast seashores; S. soda, which is mostly restricted to west coast seashores; and S. vermiculata, a perennial that occurs at one site in California and is the target of eradication.