Acalypha rhomboidea (Three-seeded mercury)

Acalypha rhomboidea Raf.

Three-seeded mercury, rhombic three-seeded mercury, rhomboid mercury, rhombic copperleaf

Kingdom	Plantae	Plants, but not fungi, lichens, or algae
Subkingdom	Tracheobionta	Vascular plants—plants with a “circulatory system” for delivering water and nutrients
Division	Magnoliophyta	Flowering plants, also known as angiosperms
Class	Magnoliopsida	Dicotyledons—plants with two initial seed leaves
Subclass	Rosidae	Roses, legumes, proteas, dogwoods, hydrangeas, mistletoes, euphorbias, grapes, many more
Order	Malpighiales	A broad group encompassing 16,000 species
Family	Euphorbiaceae	Euphorbia or spurge family
Genus	Acalypha	Copperleaves or three-seeded mercuries; means “nettle”
Species	rhomboidea	“Diamond-shaped” leaves

About plant names...

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.

9/11/2013 · Nashua River Rail Trail, Groton Center, Groton, Massachusetts
≈ 6 × 7" (14 × 18 cm)

9/27/2010 · Nashua River Rail Trail, Groton Center, Groton, Massachusetts
≈ 7 × 11" (18 × 27 cm) ID is uncertain

See this article by Steve Brill on distinguishing among nettles and related plants. Here are some similar species:

	*Laportea canadensis*	*Boehmeria cylindrica*	You are here Acalypha rhomboidea
Common Name	wood nettle	false nettle	three-seeded mercury
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.
Range/ Zones
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.
Type	Wild	Wild	Wild

	*Pilea pumila*	*Urtica dioica ssp. gracilis*
Common Name	clearweed	stinging nettle
Plant	6-24" (15-60 cm) high, with smooth, round, translucent stems. They *do not have stinging hairs*.	24-39" (60-100 cm) high, rarely up to twice that. The entire plant is covered in stinging hairs.
Flowers	Both male and female flowers are on each plant. Fowers are ⅛" (3.2 mm) long, greenish-white or greenish-yellow, hanging in narrow bunches from the axils of the upper leaves.	Plants are monoecious—male staminate flowers appear on the same plants as female pistillate flowers. Male flowers are grayish yellow, with four tepals. Female flowers have four tepals too, but in different-sized pairs. They are gray-green and hairy. The flower clusters resemble catkins.
Leaves	Leaves occur in opposite pairs, each 1-5" (2.5-12 cm) long by ½-2½" (1.3-6.3 cm) wide. Leaves are oval-shaped and coarse-toothed, with three prominent veins and textured leaves. The leaves are bright green, usually shiny, and become yellow in the fall.	Opposite, oblong, cordate, and serrate (with sawtooth edges). They are 1-6" (3-15 cm) long.
Fruit	Tiny green seeds (achenes) sometimes have black stripes.	Each inner pair of tepals encloses a single deltoid to ovoid seed.
Range/ Zones
Habitats	Wet upland or floodplain forests, crevices in rocky canyons, and shady wetlands, streambanks.	River deltas, floodplains, margins of deciduous woodlands, fencerows, and waste places
Type	Wild	Wild

Online References:

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

Acalypha on

References:

Newcomb, Lawrence, Morrison, Gordon (Illus.), Newcomb’s Wildflower Guide, Little, Brown and Company, 1977, p. 416

9/1/2013 · Trail Near James River, Midlothian, Virginia
≈ 5 × 8" (12 × 19 cm)

9/27/2010 · Nashua River Rail Trail, Groton Center, Groton, Massachusetts
≈ 4 × 6" (10 × 15 cm) ID is uncertain

9/1/2013 · Trail Near James River, Midlothian, Virginia
≈ 7 × 4½" (17 × 11 cm)

8/18/2012 · Nashua River Rail Trail, Groton Center, Groton, Massachusetts
≈ 4½ × 7" (11 × 17 cm) ID is uncertain

8/18/2012 · Nashua River Rail Trail, Groton Center, Groton, Massachusetts
≈ 4 × 6" (10 × 15 cm) ID is uncertain

8/18/2012 · Nashua River Rail Trail, Groton Center, Groton, Massachusetts
≈ 3½ × 5" (9.2 × 13 cm) ID is uncertain

9/1/2013 · Trail Near James River, Midlothian, Virginia
≈ 4½ × 6" (11 × 16 cm)

Acalypha virginica L. var. rhomboidea (Raf.) Cooperr.

Acalypha rhomboidea description by Thomas H. Kent, last updated 5 Oct 2021.

9/11/2013 · Nashua River Rail Trail, Groton Center, Groton, Massachusetts
≈ 6 × 7" (15 × 17 cm)

8/7/2010 · Tom and Susan’s, Pepperell, Massachusetts
≈ 3½ × 4" (9.4 × 10 cm) ID is uncertain

8/18/2012 · Nashua River Rail Trail, Groton Center, Groton, Massachusetts
≈ 4½ × 7" (11 × 17 cm) ID is uncertain

9/11/2013 · Nashua River Rail Trail, Groton Center, Groton, Massachusetts
≈ 6 × 8" (15 × 20 cm)

9/1/2013 · Trail Near James River, Midlothian, Virginia
≈ 5 × 8" (13 × 20 cm)

9/27/2010 · Nashua River Rail Trail, Groton Center, Groton, Massachusetts
≈ 8 × 11" (20 × 27 cm) ID is uncertain

Range:

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