Weak population differentiation and high diversity in Salsola tragus in the inland Pacific Northwest, USA.

Background: Salsola tragus is a widespread and problematic weed of semi-arid wheat production globally, and in the inland Pacific Northwest region of the USA. The species exhibits high levels of phenotypic diversity across its range and, at least in California USA, previous work has described cryptic diversity comprising a multi-species complex. Such cryptic diversity could suggest the potential for a differential response to management inputs between groups, and have important implications for the spread of herbicide resistance or other adaptive traits within populations.