[4] The lanceolate to lanceolate-rhombic acute leaves are alternate with slightly hairy petioles about 4 cm (1+1⁄2 in) long,[8] bluntly serrated margins, and pinnate venation.

The flowers consists of four tiny golden green upwardly bent sepals, acute to blunt in shape, and many stamens.

Female flowers consist of minute green sepals, a hairy tri-locular ovary, and three fringed styles.

[4] Acalypha rhomboidea also resembles young redroot pigweed (Amaranthus retroflexus L.), but may be distinguished from the latter by the flower clusters, bracts, and occasionally bronze-green leaves of the former.

[9] Acalypha rhomboidea is native to Eastern Canada and the Northeastern, Southeastern, and Central United States.

Three-seeded mercury can be found growing in moist to mesic black soil prairie, openings or lightly shaded areas of upland and floodplain forest, thickets, seeps, riverbanks and lake shores, limestone glades and bluffs, fields, fence rows, roadside and railroad right-of-ways, vacant lots, and waste areas.

[4] The seeds are an attractive food source for birds such as the mourning dove and greater prairie chicken.