Acalypha rhomboidea Raf.
Acalypha virginica L. var. rhomboidea (Raf.) Cooperr.
Three-seeded mercury, rhombic three-seeded mercury, rhomboid mercury, rhombic copperleaf
Three-seeded mercury is a member of the highly variable Euphorbia family. The genus, Acalypha, is from the Greek akalyphē, meaning “nettle,” because these plants resemble nettles. The species rhomboidea refers to the rhomboid shape of the leaves. Three-seeded mercury refers to the fruits—capsules with three seeds. I have no clue where “mercury” comes from though.
Plants: Plants are 6-24" (15-60 cm) tall, with a stem that is hairless or covered with fine white hairs.
Leaves: Alternate, lance-like or oval with sharp tips, 3½" (8.9 cm) × 1" (2.5 cm), with blunt serrations.
Flowers: Greenish-tan, and tiny—less than ⅛" (3.2 mm) across. Although the flowers are inconspicuous, the bracts (modified leaves) surrounding them turn copper-colored, along with the stems and leaf undersides, hence the common name “copperleaf.” Plants flower from July to October.
Fruits: A 3-lobed roughly spherical fruit containing 3 seeds.
See this article by Steve Brill on distinguishing
among nettles and related plants.
Here are some similar species:
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|Plant||24-48" (60-121 cm) high. Stems have stiff white hairs that sting if you rub against them.||4-63" (10-160 cm) high, and favor shady wooded areas. Stems are smooth, without the irritating hairs of stinging nettle.||6-24" (15-60 cm) tall, with a stem that is hairless or covered with fine white hairs. Bracts beneath flowers, stems, and leaf undersides turn copper-colored.|
|Flowers||Male flower clusters are white or greenish white, in loose branching clusters. Each flower is less than ⅛" (3.2 mm) across, with 5 petals. They appear from July to September.||Flowers occur on straight spikes that emerge from the stem, in clusters of small, inconspicuous green flowers. Each spike is often tipped by a couple of small leaves. Flowers appear from July to August.||Flowers are greenish-tan, and tiny—less than ⅛" (3.2 mm) across. They flower from July to October.|
|Leaves||Alternate, up to 4" (10 cm) × 6" (15 cm), egg-shaped, with coarse serrations.||Usually opposite or nearly so. They are roughly egg-shaped, with sharp tips and teeth. (More precisely, they are elliptic, lanceolate to broadly ovate.) The leaves are 1¾-7" (5-18 cm) × ¾-4" (2-10 cm).||Leaves are alternate, lance-like or oval with sharp tips, 3½" (8.9 cm) × 1" (2.5 cm), with blunt serrations.|
|Fruit||Oblique dry seeds.||Spiky little balls.||A 3-lobed roughly spherical fruit containing 3 seeds.|
|Habitats||Moist woods, streambanks, in rich soils||Moist, deciduous woods; wet meadows; swamps, bogs, and mashes||Open woods, moist soils, gravel bars, waste ground, roadsides, railroads.|
Acalypha rhomboidea on Missouriplants.com
Acalypha rhomboidea at Minnesota Wildflowers
Acalypha rhomboidea at Illinois Wildflowers
Acalypha rhomboidea on Southeastern Flora, the Southeastern U.S. Plant Identification Resource
Acalypha rhomboidea at the University of Wisconsin's Robert W. Freckmann Herbarium
Acalypha rhomboidea at the Lady Bird Johnson Wildflower Center
Newcomb, Lawrence, Morrison, Gordon (Illus.), Newcomb’s Wildflower Guide, Little, Brown and Company, 1977, p. 416
Acalypha rhomboidea description by Thomas H. Kent, last updated 10 Dec 2020.