Aegilops triuncialis (barb goatgrass) is an annual grass with a native range throughout Europe, Asia and the Mediterranean Basin. It has invaded the United States, where it is particularly invasive in California. It is expanding its range in the state and becoming a dominant grass in foothill grasslands of central California. It outcompetes native grasses, reduces habitat for threatened species, affects microbial communities and alters nutrient cycling dynamics. Management of this species is one of the most important issues in rangeland management in California.