We have fruit trees (tall and short) on a slope at the back of our yard. The trees include Fuji apple, Asian pear, peach, Santa Rosa plum, wax apple, guava, jujube, Cara Cara orange, lemon (don't know the variety), and something else that I can't remember right now. The trees are on drip irrigation. The soil here is rocky and pretty poor. Some trees have sweet potatoes planted as living mulch, which is keeping the soil around the tree moist. I am wondering what other groundcovers I can plant to make it more attractive than bare and sometimes weedy. Any recommendations for easy-maintenance, preferably California native groundcover plants that I can step on (and don't slip)?