Perennial herbs, seasonally dormant, with cormlike, subglobose tuber or cylindrical rhizome and tubercles usually formed around the main tuber, on the tuber around the petioles, or at the rhizome ends; with bulbils usually at lower, middle or upper portion of petioles, sometimes at both petiole and the base of the leaf blade. Leaves 1-5; petioles green, usually unspotted, sometimes spotted, sheath fairly long, very short or nearly absent; bulbils present or absent; leaf blades simply cordate, ovate, oblong, deeply trifid, or trisect, or pedatisect; leaflets oblong-elliptic to ovate-oblong; primary lateral veins of the leaf blade or of each leaflet pinnate, forming a submarginal collective vein, 1-2 distinct marginal veins also present, higher order venation reticulate. Inflorescence solitary, appearing with the leaves; peduncle green, shorter or slightly longer than petiole; spathe persistent, slightly to strongly constricted between tube and blade, except in Pinellia pedatisecta; tube convolute, narrowly ellipsoid to ovate, almost closed within by a transverse septum, except in P. pedatisecta, gaping at base; limb of spathe oblong-elliptic, boat-shaped, gaping, fornicate, green to purple, twice ormore as long as tube; spadix much longer than spathe, female zone adnate to spathe, separated from the male zone by the spathe septum, except in P. pedatisecta, and by the short, free, naked portion of spadix axis; male zone cylindric, short; terminal sterile appendix smooth, elongate-subulate, often sigmoid, long-exserted from spathe. Flowers unisexual, perigone absent. Male flowers 1-2(-4)-androus, stamens sometimes united congenitally in pairs or groups of four, short, laterally compressed; anthers sessile, connective slender, thecae ellipsoid, 2-celled, dehiscing by apical slit, rarely each pollen sac opening by a pore; pollen extruded in amorphous mass, inaperturate, spherical or subspheroidal, small to medium-sized, exine spinulose. Female flowers with ovary ovoid to ovoid-oblong, 1-locular; ovule 1, orthotropous, funicle very short; placentation basal, stylar region attenuate, stigma small, hemispheric to discoid. Berries oblong-ovoid, green, yellowish green or whitish; seeds obnapiform to ellipsoid, testa irregularly verrucose-rugulose or smooth; embryo axile, elongate, or very small and subglobose, endosperm copious.
HABIT : seasonally dormant herbs, tuber subglobose. LEAVES : few. PETIOLE : sometimes bearing tubercles near base and at apex, sheath fairly long. BLADE : usually deeply trifid or trisect or pedatisect, rarely simply cordate, ovate or oblong; primary lateral veins of each lobe or division pinnate, forming submarginal collective vein, 1-2 distinct marginal veins also present, higher order venation reticulate. INFLORESCENCE : solitary, appearing with leaves. PEDUNCLE : shorter or longer than petiole. SPATHE : constricted between tube and blade, tube convolute, narrowly ellipsoid to ovate, persistent, almost closed within by a transverse septum, gaping at base (P. tripartita), blade oblong-elliptic, boat-shaped, gaping, fornicate, green to purple. SPADIX : much longer than spathe, female zone adnate to spathe, separated from male zone by spathe septum and by short, free, naked part of spadix axis, male zone cylindric, short, terminal sterile appendix smooth, elongate-subulate, often sigmoid, long-exserted from spathe. FLOWERS : unisexual, perigone absent. MALE FLOWER : 1-androus, stamens sometimes united congenitally in pairs or groups of four, short, compressed laterally, anthers sessile, connective slender, thecae ellipsoid, dehiscing by apical slit. POLLEN : extruded in amorphous mass, inaperturate, spherical or subspheroidal, small to medium-sized (mean 25 µm., range 21-29 µm.), exine spinulose. FEMALE FLOWER : ovary ovoid, 1-locular, ovule 1, orthotropous, funicle very short, placenta basal, style attenuate, stigma small, hemispheric. BERRY : oblong-ovoid, green. SEED : obnapiform to ellipsoid, testa irregularly verrucose-rugulose or smooth, embryo axile, elongate or very small and subglobose, endosperm copious.
Seasonally dormant, tuberous geophytes; leaf blade trifid to trisect, sometimes cordate, submarginal collective vein present, fine venation reticulate; female zone of the spadix dorsally adnate to the spathe; spadix with a smooth, elongate terminal sterile appendix; spathe forming transverse partial septum between male and female zones; flowers unisexual, perigone absent; ovary 1-ovulate. Differs from Arisaema by adnation of female zone to spathe, presence of spathe transverse septum and flowers both sexes always present in spadix.
Eight species of Pinellia are present in China, the range of one of these (P. ternata, occupying the entire distribution range of the genus) extends to Korea, southern and central Japan. One species (P. tripartita) is endemic to southern Japan and the Ryukyu (Nansei-shoto) Islands. P. ternata is, moreover, naturalised in Europe, North America and Australia, P. tripartita in S Europa and Australia.
Within China the genus is absent from the North and Northwest (not present in the provinces Neimongolia, Helongjiang, Jilin, Qinghai, Xingjiang and Xizang) and confined to the East and Southeast. It has its greatest diversity in the East, where it is represented with four (Anhui, Zhejiang, Hubei) and five (Fujiang) species, respectively.