Cheatgrass could vie for the title of the most successful invasive species in North America. The weed lives in every state, and is the dominant plant on more than 154,000 square miles of the West, by one estimate. When it turns green in the spring, “you can actually see it from space,” said Bethany Bradley, an assistant professor at the University of Massachusetts, Amherst, who studies biogeography, the spatial distribution of species.

The sins of cheatgrass are many. Its tenacious seeds lodge in the eyes and gums of livestock (not to mention the ears of pets and the socks of hikers). Even a moderate infestation in a wheat field can reduce yields by up to half.

Its profusion is a big reason today’s Western fires burn more land, more frequently and with more ferocity than in the past, scientists say. Unlike well-spaced native bunchgrasses, cheatgrass — its scientific name is Bromus tectorum, or downy brome — crowds tightly together and then dies early each summer to form dense mats of tinder.

After fires, cheatgrass thrives even as native flora struggle to return.

After more than a half-century of largely failed efforts to thwart the Sherman’s march of cheatgrass, a researcher may have a powerful new weapon against it.