Acaena, also known as purple sheep's burr, purple goose leaf, and bidibid, is a genus of low-growing, perennial herbs native to New Zealand, Australia, South America, Hawaii, and California. It is a member of the rose family, and the plants produce small brown or purple flowers during early summer. In order to thrive, Acaena plants need full sunlight and well-drained soil. It is often used as a ground cover, in rock gardens, or as edging in flower gardens.
During the mid-summer months, Acaena blooms with bronze, purple, pink, or white flowers. In early summer, flower stems can grow up to 3 inches (7.62 cm) tall. It has scalloped green, bronze, or steel blue foliage, which is evergreen in warmer climates. The foliage is 2 to 6 inches (4 to 15 cm) in length, and 3 inches (7.62 cm) across.
Small burred seed balls appear in late summer in most varieties of Acaena. These burrs attach to animals and people and are carried to a variety of destinations where the seeds may be able to grow. The plants can also be propagated by separating the root ball in early spring or autumn, or by taking cuttings in late spring.
This slow-growing plant thrives in United States Department of Agriculture hardiness zones six through nine. It grows in well-drained, sandy soil. Acaena needs full sun or partial shade and an average amount of water. In colder climates, it may need winter protection and mulching. It is suitable for use in xeriscaping.
Acaena is a low-maintenance, deer-resistant plant that only requires pruning every four or five years. It is susceptible to powdery mildew and rust. To treat powdery mildew, gardeners can apply a sulfur-based fungicide at the first sign of disease. To treat rust, the diseased leaves must be removed at the first indication that the plant is sick; rust-infected leaves should not be composted. A fungicide made to treat rust, proper air circulation, and continued removal of diseased leaves should continue until the plant is rust free.
Although some gardeners regard this plant as an invasive species, others use the ground cover as an accent in alpine and rock gardens, or as edging in garden beds. Some gardeners also use Acaena in container gardens. It does not tolerate foot traffic. A path to protect the plant from being trampled may be needed if this plant is used in a garden area where people walk.