Tumbleweed (Salsola tragus) is also known as Russian Thistle and Russianbarbwire Thistle. Although often used as a symbol of the West, this spiny plant is in reality an exotic and invasive species from Eurasia. In autumn the plant breaks off at ground level and tumbles across the landscape in the wind, scattering thousands of seeds. It is thought to have entered the US in the 19th century as a contaminant in shipments of flax seeds. Photo White Pine Co., NV.