Arundo donax is a very large plant that might be found growing as a dense stand in water, topped by very large, feathery, plume-like inflorescences. Giant reed is a source of reeds for musical instruments and industrial cellulose.
Giant reed is a non-native large grass. The rhizomes hard and thick; stems cane-like, tall, erect or leaning, to 20 ft. tall, 2 in. thick; leaf bladesnumerous, stiff, to 3 ft. long, to 2 in. wide, smooth, rounded at base, tapering to a long point; sheaths smooth; ligules large, papery, small hairy margin; inflorescence a dense erect loose spike, to 2 ft. long, feathery, whitish to brown; spikelets stalked, solitary; flowers with long silky hairs (awns).