Tall woody bamboo, stems thorny, numerous, tufted, up to 40 m tall, curving at top; branches numerous, internodes 30 to 45 cm long, prominent, bearing in lower parts of stems dense half whorls of stiff, naked, horizontal branches, armed with recurved, stout spines; lowest nodes rooting; stem-sheaths leathery, orange-yellow when young, hairy outside, shining and ribbed inside, 30 to 45 cm long; blade triangular, glabrous, covered with a brown felt of bristly hairs inside; leaves thin, linear, up to 20 cm long, glabrous above, hair beneath; leaf-sheaths hairy, small; inflorescence an enormous panicle, often occupying the entire stem; branchlets loose clusters of pale, glabrous spike.