Regarding a recent MHB, a reader notes:
Interesting factoid about tumbleweeds: As iconic as they are in Westerns, they're actually a non-native exotic species imported from Eurasia in the 19th century. They've been here long enough that no one alive today remembers what the American West looked like without them. They're harmful to the environment in at least two ways. First, they compete with other plants for precious water, and then when they break off and start rolling, they damage the crust of soil, which has the ironic effect of making better growing conditions for the next generation of tumbleweeds since they thrive in disturbed soils.
But they can also help the environment:
[M]ost tumbleweed species grow quickly and outcompete other types of plants. In one study, for example, Russian sage sucked up an average of 44 gallons of water when competing with wheat, which can be the difference between a good wheat harvest and a bad one. However, this thirstiness and ability to remove chemicals from the ground could be useful. For example, another species of Russian sage, Salsola kali, accumulates high levels of various toxic pollutants, which might allow it to help clean up contaminated sites.
The Dish 