Tumbleweeds rolling? Must be a western. The cinematic signal of high plains desolation has an even more pernicious side: it’s an invasive species known as Russian Thistle, and it’s wreaking havoc across the United States. George Johnson is a writer based in Santa Fe, and a regular contributor to National Geographic, where he wrote about fighting the tumbleweed menace in his own backyard. To see more photos click here.