The understory and riparian shrub cover feature snowberry, spiraea, ninebark, serviceberry, and red-twig dogwood. The larvae feed on plants including honeysuckle, viburnum, hawthorn, snowberry, cherry, mint, and plum. They damage also the fruits of apricot, honeysuckle, barberry, bird cherry and snowberry. The tributary canyons feature mockorange, poison-ivy, red-twig dogwood, snowberry, and Rocky Mountain maple. The chaparral features Oregon grape, western fescue, snowberry, bluebunch wheatgrass, and ceanothus. The ground cover includes snowberry, Oregon grape, salal, sword fern, trillium, and fawn lily. Wetter oak woodlands historically had a substantial shrub understory, primarily snowberry. Understory species include oceanspray, Western poison-oak, snowberry, Idaho fescue, California brome, roughstalk bluegrass, and ceanothus. Understory plants include Idaho fescue, antelope bitterbrush, Ross' sedge, western fescue, snowberry, and golden chinkapin. Understory plants include snowberry, heartleaf arnica, Wheeler bluegrass, antelope bitterbrush, and longstolon sedge. Common understory plants included California fescue, snowberry, and serviceberry. Other common shrubs include bitterbrush, snowberry, and ceanothus. At higher elevations, greenleaf manzanita and snowberry are found. Plants in the understory include vine maple, hazel, snowberry, and oceanspray. Shrubs that survive among them include strawberry, snowberry, willows and bog birch.