A genus of flowering plants in the family Euphorbiaceae. It is the sole genus of the subtribe Acalyphinae. It is one of the largest euphorb genera, with approximately 450 to 462 species. The genus name Acalypha is from the Ancient Greek ἀκαλύφη (akalúphē) (“nettle”), an alternative form of ἀκαλήφη (akalḗphē), and was inspired by the nettle-like leaves. General common names include copperleaf and three-seeded mercury. Native North American species are generally inconspicuous most of the year until the fall when their stems and foliage turn a distinctive coppery-red.