Groundcovers can be shrubs, perennials, vines, ferns or grasses. Any plant that spreads along the ground and does not grow to over two feet in height can be considered a groundcover. Larger spreading plants can also be used as groundcovers in large scale landscapes. Groundcovers are often used to control erosion on hillsides, as barriers, and to cover large areas of yard flowing around and between larger shrub and tree plantings. Groundcover plants are increasingly used as alternatives to water thirsty lawns.