Perennial herb, with trailing or ascending branches rooting at thenodes.  Leaves opposite, sessile, elliptical to obovate, 2-12 cm x 1-6 cm, apex acute,cuneate at the base, marginsserrate-dentate often lobed; inflorescence a capitulum on axillary or terminal peduncles; ray florets bright yellow; achenes 5mm long, oblong to obovoid, compressed.

Tufted perennial grass with aromatic roots.  Culms 1-2 m high.  Leaves linear, 30-100 cm x 4-10 mm, margins scabrous, blade glabrous. Panicles long-pyramidal up to 20-35 cm long with many branches in several whorls, spikelets awnless, 4-5 mm long no bristles.

Herb 40-70 cm high, forming large colonies, stems thick and covered with withered leaves. Leaves alternate, sessile, densely imbricate, linear-lanceolate, 20-35 x 3-5 cm, dark green above, purple beneath and along the margins; inflorescence axillary,  umbelliform cyme enclosed by compressed spathe-like bracts, 3-4.5 cm broad and 2-3 high, petals white 5-8 mm long; capsule 3-angled 4.5 mm long.