Ontario Weeds: Three-seeded mercury

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Excerpt from Publication 505, Ontario Weeds, Order this publication

Table of Contents

  1. Name
  2. Other Names
  3. Family
  4. General Description
  5. Stems and Roots
  6. Flowers and Fruit
  7. Habitat
  8. Similar Species
  9. Related Links

Name: Three-seeded mercury, Acalypha rhomboidea Raf.,

Other Names: ricinelle rhomboide, Copperleaf, rhombic copperleaf, ricinelle de Virginie

Family: Spurge Family (Euphorbiaceae)

General Description: Annual, reproducing only by seed.

Photos and Pictures

Three-seeded mercury.

Three-seeded mercury. A. Plant. B. Portion of fruiting stem showing 1 three-seeded fruit developing from 1 of 4 flowers in a leaf axil.
Three-seeded mercury.
A. Plant. B. Portion of fruiting stem showing 1 three-seeded fruit developing from 1 of 4 flowers in a leaf axil.

Stems & Roots: Stems erect, 7.5-100cm (3-40in.) high, simple or branched, slightly hairy; leaves green to bronze-green, 1-9cm (2/5-3½in.) long, lance- to rhombic-ovate on petioles that are 1/3 the length to almost as long as the leaf blade; margins with irregular, rounded teeth.

Flowers & Fruit: Flowers in greenish clusters in axils of leaves, each cluster composed of one or more palmately cleft bracts with 5 to 9 lobes, one or more stalked male spikes 4-15mm (1/6-2/5in.) long and one or more shorter female flowers; seedpods deeply 3-lobed (similar to those of Leafy spurge) and containing 3 seeds; seeds tan coloured, 1.6-1.8mm (1/15in.) long. Flowers from July to September.

Habitat: Three-seeded mercury occurs in dry or moist soil in open woods, fields, waste places, ditches and roadsides throughout south-central Ontario.

Similar Species: It resembles young plants of Redroot pigweed but is distinguished by its flowers borne in axillary clusters with bracts having 5-9 lobes and its leaves occasionally a bronze-green colour.

Related Links

... on general Weed topics
... on weed identification, order OMAFRA Publication 505: Ontario Weeds
... on weed control, order OMAFRA Publication 75: Guide To Weed Control

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For more information:
Toll Free: 1-877-424-1300
E-mail: ag.info.omafra@ontario.ca
Author: OMAFRA Staff
Creation Date: 01 June 2000
Last Reviewed: 01 November 2003