606; see text Pilea, with 600–715 species, is the largest genus of flowering plants in the nettle family Urticaceae.

The majority of species are shade-loving herbaceous plants 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).

[citation needed] Six species have horticultural value (P. cadierei, P. grandifolia, P. involucrata, P. microphylla, P. nummulariifolia, and P. peperomioides),[2] Some pileas are grown for their ornamental foliage which is shaped like lily-pads.

[4] The genus has attracted little monographic attention since Weddell (1869), and the majority of taxonomic contributions have come from floristic treatments.

The genus name Pilea is Latin for "felt cap", a reference to the calyx covering the achene.