I’ve always known, in very general terms, that the tumbleweed is an interloper. But the story is better than I could possibly have hoped. From Tim Egan’s The Worst Hard Time (a book I’m just catching up with and wondering what took me so long):

[W]hen they boarded ships for America, the Germans from Russia carried with them seeds of turkey red – a hard winter wheat – and incidental thistle sewn into the pockets of their vests. It mean survival, an heorloom packet worth more than currency. The turkey red, short-stemmed and resistant to cold an drought, took so well to the land beyond the ninety-eighth meridian that agronomists were forced to rethink the predominant view that the Great American Desert was unsuited for agriculture. In Russia, it was the crop that allow the Germans to move out of the valleys and onto the hihher, drier farming ground of the steppe. The thistle came by accident, but it grew so fast it soon owned the West. In the Old World, thistle was called perekati-pole, which meant “roll-across-the-field.” In America, it was knonw as tumbleweed.

Tim Egan is a very good storyteller