pampas grass Species of tall, reed-like grass native to South America and widely cultivated in warm parts of the world as a lawn ornamental. Female plants bear flower clusters, 91cm (3ft) tall, which are silvery and plume-like. Family Poaceae/Gramineae; species Cortaderia selloana.

pam·pas grass / ˈpampəs/ • n. a tall South American grass (Cortaderia selloana) with silky flowering plumes, widely cultivated as an ornamental plant.