Arisaema rubrirhizomatum H.Li & J.Murata

Plants basically dioecious. Rhizome erect, oblique, or horizontal, dark brown outside, purple in section, cylindric or conic, 2–5 × 1–2cm. Cataphylls 3, encircling pseudostem, lanceolate, membranous, outermost one 1–2cm, innermost one 18–19cm. Leaves 1 or 2; petiole purplish green or olive-green with pale green spots, 30–50cm, proximal 20–30cm sheathing into pseudostem; leaf blade green, leathery, 3-foliolate; central leaflet with petiolule 1–4cm, blade elliptic or oblong to lanceolate, 12–26 × 5–12cm, base cuneate; lateral leaflets sessile or with short petiolule 1–4cm, blade oblong-lanceolate or obliquely ovate, 10–20 × 3.5–11cm, apex acuminate. Peduncle colored as petiole, slightly longer than petioles, 30–50cm. Spathe green with a white area ca. 2cm in diam. at proximal part of limb; tube 3–5 × 1.5–1.8cm, throat spreading outward; limb deltoid-ovate, 5–7 × 3.5–5cm, apex acute. Spadix basically unisexual; female zone ca. 2.2 × 1.5cm; ovary obconic; ovules 2–4; synandria of 5 stamens, sessile; male zone ca. 3.5cm × 5mm, rarely with a few male flowers above; anthers ovoid, dehiscing by 2 apical slits; appendix dark purplish, 4–5cm, slender, from base to apex covered with rather numerous filiform or subclavate neuter flowers, brushlike. Berries reddish, ovoid, ca. 5mm in diam. Seed 1, yellowish, ca. 3.5 mm in diam., rugose.