Pinellia
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.
Chromosome numbers of six species are reported in the literature (for references see species treatments, below). According to these reports diploid and polyploid cytotypes are known, partly from the same species. Pinellia yaoluopingensis and P. pedatisecta are diploid (with 2n = 26, x = 13), P. peltata is hexaploid (2n = 78), P. tripartita diploid (2n = 26) or tetraploid (2n = 52).
In P. cordata a polyploid cytotype with 2n = 72 is known, which can be interpreted as hexaploid with aneuploid reduction from 2n = 78. P. ternata forms a polyploid complex, which contains various ploidy levels up to decaploids (2n = 130) and extensive aneuploid series. All species of Pinellia so far seem to have a basic number of x = 13 (for further details see under P. ternata).
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.