Naturvidensk. Math. Afd., ser. 5, 2: 296. 1851.
Herbs, annual or short-lived perennial, 0.3-2 dm. Stems 10-40-branched, erect. Leaf blades spatulate to obovate, paired blades unequal, the larger 3-10 × 1.5-5.5 mm, the smaller 1.5-4 × 0.7-2 mm, margins entire. Inflorescences crowded. Flowers ca. 0.5 mm across. Achenes uniformly light brown, slightly compressed, ovoid-cylindric, ca. 0.5(-1.1) × 0.3 mm, smooth.
Phenology: Flowering all year.
Habitat: Waste places, hammocks, rocky woods, cultivated plots, on masonry
Elevation: 0-100 m
Fla., Ga., La., S.C., Mexico, West Indies, Central America, tropical South America, Pacific Islands (Hawaii), Asia.
Pilea microphylla has been collected once in Tennessee and once in Michigan, but it is unlikely that the species persists so far north. It is widely grown as a houseplant in the north and a border plant in the south. It is a greenhouse weed in various parts of the flora.