Anisantha tectorum (Cheatgrass)
Cheat grass, a fire hazard, probably has a symbiotic reltionship with fire. Its awns can be injurious to animals.
Cheat grass was introduced very early (an undocumented report comes from 1790) as a contaminant in packing material and grain imports. The photo above shows a meadow overtaken by cheat grass, with populations of Wooly Mullein and thistles as well. Such a meadow is almost certainly beyond reclamation.