Pilea with 600715 species is the largest genus in the plant family Urticaceae and one of the larger genera in the Urticales and eudicot rosids. It is distributed throughout the tropics, subtropics, and warm temperate regions (with the exception of Australia and New Zealand). The majority of species are succulent shade-loving herbs or shrubs, which are easily distinguished from other Urticaceae by the combination of opposite leaves (with rare exceptions) with a single ligulate intrapetiolar stipule in each leaf axil and cymose or paniculate inflorescences (again with rare exceptions). Pilea is of little economic importance; four species are of minor horticultural importance (P. cadierei, P. involucrata, P. microphylla, and P. peperomioides) and one species is used in Chinese traditional medicine (P. plataniflora). The genus has attracted little monographic attention since Weddell (1869), and the majority of taxonomic contributions have come from floristic treatments.
Contributions by SB Johnny, Tiggrx, and Bochkov.