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Rhomboid Mercury (Acalypha rhomboidea)

Also known as common threeseed mercury.

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Rhomboid Mercury

Summary

Also called Common Threeseed Mercury. An annual plant native to North America; common and widely distributed. An inconspicuous, weedy plant that nearly everyone in its range has seen, but few people notice or know how to identify.

Range - Expand

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Native

This tentative map is based on the FHWA's ERA. This data lacks information on Canada, but also overestimates native ranges, especially around the edges, as this post explains. We have not yet reviewed or fixed this map.

Similar Plants

thumbnail of Virginia Threeseed Mercury
Virginia Threeseed Mercury (Acalypha virginica)
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Habitat

A generalist, found in a wide range of habitats, but prefers disturbed habitats, particularly those influenced or managed by humans.

Common, often abundant in vacant lots, industrial areas, roadsides and railroad margins, and parks, and is a common garden weed. Because of its later emergence, it usually cannot survive competition from other plants that sprout earlier.

This plant has benefitted greatly from humans' alteration of the environment; the mowing, trimming, tilling of garden soil, or clearing of plants once the growing season has already gives it an opportunity to take hold.

Life Cycle

A strict annual, this plant sprouts from seed each year. Plants often do not emerge until the warmer temperatures of late spring or early summer, when other vegetation has already grown considerably. As such this plant is most likely to germinate in areas where competing vegetation was either sparse to begin with, or where some disturbance (typically in late spring to early summer) removed competing vegetation.

Plants start blooming mid-summer and often continue blooming and producing seed incrementally until a frost. Flowers are inconspicuous and probably wind-pollinated.

Faunal Associations

The relatively large seeds support mourning doves and other seed-eating birds.

The leaves usually show evidence of insect damage, although we have so far been unable to find information on which insects eat this species.

There are numerous Acalypha species found in North America; most are native but there are a few introduced species in isolated areas. The most common overlapping species are Acalypha virginica, which is usually slightly less common, and Acalypha gracilens, which is progressively slightly less common.

The broader Euphorbiaceae family contains even more plants found in North America, but these plants share less in common with the Acalypha species ecologically, in part because the Acalypha species have lost the toxic sap characterizing most of the Euphorbiaceae family.

Acalypha rhomboidea (Rhomboid Mercury) | Illinois Wildflowers (About This Site)

Acalypha rhomboidea (Rhomboid Mercury) | USDA PLANTS Database (About This Site)

Acalypha rhomboidea | Go Botany (About This Site)

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