Three-Seeded Mercury

Spurge (Euphorbiaceae family):

Acalypha rhomboidea Raf.

EPPO code:

ACCRH

Other names:

Copperleaf, rhombic copperleaf

Species information

Lifecycle:

Annual.

Propagation:

Reproduces by seed.

Emergence:

Three-seeded mercury is not considered an early germinating species. Typically, it emerges in late spring.

Habitat:

Most common in south-central Ontario, three-seeded mercury is most often found around field boundaries, near open woods. It can, however, be found in cultivated crops, ditches, and road sides.

Identification clues

Seedlings

Cotyledons:

Orbicular, with a slightly indented apex and clearly visible veins.

First leaves:

Three-sided mercury’s first leaves are opposite and ovate with round toothed margins. Leaves appear glossy and are green to copper in colour.

Mature leaves:

The mature leaves of three-seeded mercury have an alternate leaf orientation, and are similar in appearance to its younger leaves, only larger and with more prominent veins.

Mature plant

Stems:

Erect, sparsely haired to hairy.

Flowers:

Male and female flowers are produced separately on the same plant (monoecious). They are green and clustered in leaf axils. The plant’s seedpods are deeply tri-lobed and contain the “three seeds” referred to in its common name.

Seeds:

Seeds are egg-shaped, range in length from 1.5–2 mm, and are tan coloured with spots.

Roots:

Taproot.

Often mistaken for

I know it's not Pigweed species because three-seeded mercury has round cotyledons, a glossy bronze-green leaf colour, toothed leaf margins and clusters of greenish flowers at each axil.