Acalypha rhomboidea
common three-seeded mercury
Native to North America
SunFull Sun – Part Shade
WaterMedium
Overview
Acalypha rhomboidea is an annual herb 4-24 inches (10-60 cm) tall, with a slender erect to branching reddish-green stem that often flushes deep red in sun. The alternate leaves are thin, rhombic to ovate, 1-3 inches (2.5-7.5 cm) long, carried on long petioles, with toothed margins and a tendency to droop in drought. It is monoecious, holding separate male and female flowers in the same axillary spikes; the small greenish flowers have no petals and sit within a cupped, deeply lobed leafy bract that enlarges as the fruit develops. Each pollinated flower forms a three-lobed capsule about 0.1 inch (3 mm) wide holding three seeds, the source of the common name. Flowering runs from midsummer to frost, and a single plant can set hundreds of seeds that persist in the soil. The species is a common weed of gardens, croplands, roadsides, and disturbed woods across eastern North America, germinating in warm soil after the last frost. One trade-off in any planting is its weediness, since it self-sows freely and competes with slower seedlings.
Native Range
Native to eastern and central North America, from Quebec and Ontario south to Florida and Texas. It grows in disturbed ground, gardens, fields, roadsides, and open woods, mostly on moist to average soils.Suggested Uses
Rarely planted on purpose, it appears as a volunteer in cultivated ground and is recorded in native-plant and weed surveys. It serves as a minor seed source for ground-feeding birds and as a larval host for some moths.How to Identify
Appearance
Size & Dimensions
Height4" - 2'
Width/Spread4" - 1'
Bloom Information
Detailed Descriptions
Foliage Description
Green, often red-tingedGrowing Conditions
Sun Requirements
Requires 3-8 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight
Water & Climate
Water Needs
Care & Maintenance
Care Guide
Grows in full sun to part shade on a wide range of moist to average soils at pH 5.5-7.5, and tolerates poor compacted ground. As a warm-season annual, seed germinates once soil warms past about 60F (16C) after the last frost. Plants need no fertilizer and little care, completing their cycle in a single season. In gardens it behaves as a volunteer weed, so shallow cultivation or mulching while seedlings are small keeps numbers down. Plants pull up easily by hand before they set seed.Pruning
Pruning is not applicable to this annual. Removing plants before the capsules ripen prevents seed from building up in the soil. Cut or pulled plants do not regrow.⚠️ Toxicity Warning
UnknownPlanting Guide
Planting Methods & Timing
Planting Method
direct sow
Direct Sow Timing
After the last frost when soil reaches about 60F (16C)
Days to Maturity
55–75 days
Plant Spacing
6 inches