Description from Flora of China
Arum flagelliforme Loddiges, Bot. Cab. 4: t. 396. 1819; A. cuspidatum Blume; Typhonium cuspidatum (Blume) Decaisne.
Underground part a short, tuberous rhizome, depressed, 1-2 cm. Petiole green, 15-30 cm; leaf blade 5-25 × 0.5-18 cm, extremely variable, linear, lanceolate, elliptic, or hastate. Inflorescence appearing alongside leaves; peduncle 5-20 cm, thin. Spathe convolute at base, green, ovoid, globose, or depressed, 1.5-3.5 × 1.2-2 cm, constricted at apex, outside with 1 or a few keels; limb convolute-tubular at base, expanded and sharply flexed horizontally at apex, green on both sides or base flushed purple, lanceolate, 7.5-25 cm, tapering to long acuminate apex. Spadix shorter than, as long as, or slightly longer than spathe; female zone subcylindric, slightly fusiform, 1.5-1.8 cm × 8-10 mm; ovary pale green, elongate, angulate; sterile zone 1-2 cm, entirely covered with staminodes, these distant; staminodes dimorphic; proximal ones ca. 6 mm, with a horizontal white base, apically sharply upcurved, spatulate-lingulate and with or without a purple apex; distal ones downcurved, white, subulate, aristate; male zone ca. 5 mm; appendix subsessile, 16-17 cm, base swollen and often deeply grooved, apically filiform, erect, horizontal, or downcurved. Berries pale greenish, 2- or 3-seeded. Fl. Apr-May.
In shallow water by streams, water fields, moist meadows; sea level to 400 m. Guangdong, Guangxi, SE Yunnan [Bangladesh, Bhutan, Cambodia, NE and S India, Indonesia, Laos, Malaysia, Myanmar, Philippines, Singapore, Sri Lanka, N Thailand; N Australia].