Of China and Japan, is reported to be established as a weed in Wis. It resembles P. americana in aspect, but has 8 stamens and 8 distinct carpels. The carpels ripen into distinct frs, each with a thin dry pericarp and a large black seed, the set of frs collectively no larger than a berry of P. americana; 2n=36. (P. esculenta)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.