Some call it a weed. Others see it as an attractive option for ground cover, or as a way to improve lawns. For those in the latter category, clover (Trifolium spp.) is appealing for its fast growth and its ability to naturalize and fix nitrogen in the soil. The species familiar to most home gardeners is white clover (Trifolium repens), which is hardy in U.S. Department of Agriculture plant hardiness zones 3 through 10. White clover is not invasive in dry climates, but rose clover (Trifolium hirtum) is, according to the University of California Davis Invasive Plant Inventory.