Acmella repens
oppositeleaf spotflower
Southeastern US and tropical America
Overview
Acmella repens is a low, creeping herbaceous perennial with slender stems that root at the nodes and form spreading mats 4 to 12 inches (10 to 30 cm) high. The opposite, oval to triangular leaves are 1 to 2.5 inches (2.5 to 6 cm) long, with toothed margins. Through the warm season it produces cone-shaped to rounded yellow flower heads on long stalks, each head about 0.3 to 0.5 inch (8 to 13 mm) high, with short yellow ray florets or none. The plant grows in moist, disturbed ground such as lawns, ditches, pond edges, and stream banks from the southeastern United States through tropical America. Like its relatives, the flower heads contain compounds that cause a tingling, numbing sensation if chewed. It roots as it spreads and can move into lawns and beds as a weed. It needs moist soil and full sun to part shade. The creeping habit makes it hard to confine.
Native Range
Native to the southeastern United States and through Mexico, Central America, and South America. It grows in moist, disturbed ground including lawns, ditches, pond margins, and stream banks.Suggested Uses
Used as a groundcover in moist, informal areas and at pond edges in warm climates. It tolerates light foot traffic and fills damp ground where turf struggles. Its spreading habit suits naturalized sites rather than formal beds.How to Identify
Appearance
Size & Dimensions
Height4" - 1'
Width/Spread1' - 2'
Bloom Information
Flowering continues through the warm season, from late spring into autumn in mild climates. Yellow, cone-shaped to rounded heads open on long stalks above the foliage. Bloom and seed set overlap for many weeks. Flowering slows in cool weather and stops at frost.
Detailed Descriptions
Foliage Description
greenGrowing Conditions
Sun Requirements
Requires 4-10 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
Care & Maintenance
Care Guide
Grow in full sun to part shade in moist, fertile soil. Acmella repens accepts loam, sand, or clay with a pH from 5.5 to 7.0 and needs steady moisture. It spreads quickly by rooting stems and can move into lawns and beds, so a contained or damp site is appropriate. It is hardy in USDA zones 8 through 11 and is killed or knocked back by hard frost. Water in dry spells to keep growth dense. Mow or shear to control spread where needed.Pruning
Mowing or shearing keeps the mat low and limits spread. Spent flower stalks can be removed to reduce self-seeding. Rooting runners can be cut back at the edges of a planting. The plant regrows quickly from nodes and roots.Container Growing
✓ Suitable for container growing
Minimum container size: 1 gallons