Three-Seeded Mercury

Kendall County (IL) Forest Preserve District

Three-Seeded Mercury (Rhomboid Mercury)
Acalypha rhomboidea [C-value 0]
Spurge family (Euphorbiaceae)
Blooms mid-August - September

The native Three-Seeded Mercury is common in our area. It prefers light shade to full sun and moist to slightly dry fertile loamy soil. Habitats include disturbed areas of moist prairies, seeps and stream banks. This annual is ½–2' tall, usually unbranched with a central stem having lines of fine white hairs. The alternate leaves are up to 3½" long and 1" across and bluntly toothed with conspicuous pinnate venation. Where the petiole of each leaf meets the stem, there is a conspicuous bract that wraps around the inflorescence consisting of a green cyathium with tiny staminate and pistillate flowers without sepals and petals.

Three-Seeded Mercury at Lyon Forest Preserve September 14, 2014

Each pistillate flower produces a 3-lobed spheroid fruit that is typical of the spurges. Each fruit contains three seeds - hence the common name.

Three-Seeded Mercury at Lyon Forest Preserve October 31, 2014

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