Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

Russian thistle (Salsola) species in western United States.

Abstract

Russian thistle (S. kali) populations widespread in the western USA have been found to consist of 2 distinct species, S. iberica (abundant on disturbed land above 6000 ft, especially on sandy soils of volcanic origin) and S. paulsenii (prevalent on disturbed land below 4000 ft, especially on limestone-derived soils), although hybridisation occurs freely, with various degrees of introgression. Characteristic features of the 2 species are described.