Acaena inermis 'Purpurea'
Common name: Purple New Zealand Burr, Spineless Pirri-pirri Burr.
Zone (4) 6 to 9 (10).
Full sun to part shade.
Plants reach 2 to 4 inches tall and 12 to 24 inches wide,
semi-evergreen perennial subshrub ground cover.
Growth rate: rhizomatous roots of this plant spread moderately fast.
Carpet of 3-inch-wide, purple-brown to pale olive leaves have a feathery, fern-like texture and scalloped edge; when planted in full sun, foliage may turn ruby-red. Small creamy-brown burr-shaped flowers appear in summer followed by brown-red fruits.
Acaena inermis 'Purpurea' tolerates most well-drained soils. Clip or mow back in early spring to stimulate spring growth. It is easily propagated by dividing ('ripping' apart) in spring or early fall.
Excellent cascading effect over rocks and walls, Acaena inermis 'Purpurea' can be a little invasive. Planted between stepping stones, it tolerates light foot traffic.