三裂叶半夏 san lie ye ban xia

Atherurus tripartitus Blume, Rumphia 1: 137. 1835; Arisaema tripartitum (Blume) Engler; Pinellia tripartita var. atropurpurea Makino.

Tuber subglobose, ca. 2.5 cm in diam.; cataphylls lanceolate, to 10 cm. Leaves 2-5; petiole green, 30-35 cm; leaf blade green, 3-partite; leaflets broadly ovate to ovate-oblong; anterior leaflet ca. 15 × 4-7 cm, apex ca. 1.5 cm; lateral leaflets smaller; primary lateral veins 8-12 per side on each leaflet, forming a distinct marginal collective vein, also with 2 thinner collective veins along margin. Inflorescence solitary; peduncle to 25 cm, shorter than petioles, slender. Spathe whitish to light green, slightly constricted, 7-9(-10) cm; tube almost closed within by a transverse septum, gaping at base, oblong to subcylindric, ca. 3.5 × 1-1.25 cm; limb gaping, boat-shaped, oblong, ca. 4 × 2.5 cm. Spadix 20-25 cm; female zone ca. 3 cm, adnate to spathe; female flowers densely arranged; pistil 1-1.2 mm; ovary ovoid, 0.9-1 mm; style distinct, 0.2-0.3 mm, attenuate; stigma subhemispheric; sterile zone between female and male zone 0.6-0.7 cm; male zone 1.8-2 cm; thecae elongate, opening by a slit; appendix long exserted from spathe, sigmoid, 15-20 cm, base ca. 3 mm in diam., smooth. Berries pale green to whitish, ovoid, 1-seeded. Fl. May-Jul, fr. Jun-Sep. 2n = 26, 52.

Dense broad-leaved forests, forest margins, roadsides. Hong Kong [Japan].

Pinellia tripartita was considered endemic to Japan for a long time; it is first reported here from Hong Kong (C. Wright 508, P).

This species differs from Pinellia yaoluopingensis in having broadly ovate or ovate-oblong, sessile leaflets and a tuber lacking tubercles. It is also easily distinguishable from P. ternata by its petioles lacking bulbils.

This species is used ornamentally.