Western Poison Oak

This climbing vine has lobed leaves, dangling inflorescence and uses clinging roots to hold on (third image). "Western poison oak is extremely variable in growth habit and leaf appearance. It grows as a dense shrub in open sunlight, a tree with an 8–20 cm (3.1–7.9 in) trunk under conditions with ample sunlight, very wet winter/spring and dry summer, or as a climbing vine in shaded areas. Like poison-ivy, it reproduces by creeping rootstocks or by seeds.[2] The leaves are divided into three (rarely 5, 7, or 9) leaflets, 3.5 to 10 centimetres (1.4 to 3.9 in) long, with scalloped, toothed, or lobed edges — generally resembling the leaves of a true oak, though the western poison oak leaves will tend to be more glossy. Leaves are typically bronze when first unfolding, bright green in the spring, yellow-green to reddish in the summer, and bright red or pink in the fall. White flowers form in the spring and, if fertilized, develop into greenish-white or tan berries. T. diversilobum is winter deciduous, so that after cold weather sets in, the stems are leafless and bear only the occasional cluster of berries. Without leaves, poison oak stems may sometimes be identified by occasional black marks where its milky sap may have oozed and dried." - Wikipedia