Description from Flora of China
Arisaema dilatatum Buchet; A. rhombiforme Buchet.
Plants dioecious. Tuber subglobose, 2-5 cm in diam. Cataphylls usually 2, reddish brown, to 13 cm, acute. Leaf solitary; petiole green, 20-30 cm, often verrucose, base forming pseudostem, ca. 2 cm in diam.; leaf blade 3-foliolate; leaflets green with cristate margins; central leaflet sessile, obovate to obcordate, 5-10 × 6-13 cm, base narrowly cuneate, apex abruptly acute; lateral leaflets obliquely oblong or ovate, 7-14 × 5-10 cm, base broadly cuneate, apex acute. Spathe purple with green or whitish stripes; tube cylindric, 3-5 × 2-2.5 cm, throat margins obliquely truncate, neither recurved nor auriculate; limb incurved or suberect, dark purple, oblong, 7-10 × ca. 4 cm, apex abruptly acuminate. Peduncle green, 11-15 cm, often verrucose. Spadix unisexual; female zone cylindric, ca. 2 × 1.2 cm; ovary green, oblong-ovoid; style green, short; stigma white or purple, pilose; male zone cylindric, ca. 3 × 1.1 cm; synandria stipitate; stipe reddish, 2-3 mm; anthers 2-5, yellow, obovoid, dehiscing by a horseshoe-shaped slit. Appendix sigmoid, to 20 cm in total, proximal 4-5 cm whitish or purplish to dark purple, cylindric, ca. 8 mm in diam., abruptly narrowed at base into stipe ca. 8 mm, distally narrowed into flagellum. Berries red, oblong. Seeds 5-8, pale brown, ovoid. Fl. Jun-Jul, fr. Aug.
Coniferous forests, bamboo forests, meadows, usually among mossy rocks; 1800-4000 m. Chongqing, Gansu, Guizhou, Sichuan, Xizang, Yunnan [Bhutan, Myanmar].