Arisaema thunbergii subsp. autumnale J.C.Wang, J.Murata & H.Ohashi

Plants dioecious. Tuber depressed globose, 3–6cm in diam. Cataphylls purplish to brownish, membranous, apex mucronate. Leaf solitary; petiole terete, 25–50cm, proximally forming pseudostem; leaf blade pedate; leaflets 11–15, oblanceolate to elliptic, base cuneate, apex acuminate; central leaflet 10–28 × 2–7.5cm. Peduncle usually shorter than petioles, 15–35cm. Spathe white or pale yellow with dark to bronze-purple or reddish purple stripes; tube white or pale yellow with longitudinal purple stripes outside and dark purple stripes inside, cylindric, auriculate at throat, 5–7 × 2–2.5cm; limb triangular-ovate, 7–10 × 4–5cm, apex acute to acuminate. Spadix unisexual; female zone cylindric, 1.5–2cm; male zone 3–4cm; synandria stipitate, consisting of 4 anthers, thecae dehiscing from lateral slits. Appendix long exserted from spathe, filiform, 40–60cm, proximally narrowly cylindric, smooth, gradually narrowed at both ends, distally bent downward and pendulous.