billion-dollar grass

== English == === Etymology === Probably so-called because of the adverse impact of Echinochloa weeds on yields rice and other crops. === Noun === billion-dollar grass (countable and uncountable, plural billion-dollar grasses) Any of the genus Echinochloa of barnyard grass, widely considered harmful weeds. === References === Echinochloa on Wikipedia.Wikipedia Echinochloa on Wikispecies.Wikispecies Category:Echinochloa on Wikimedia Commons.Wikimedia Commons