The California Box Elder, also known as Acer negundo var. californicum, is a deciduous tree native to northwestern Mexico and southwestern United States. There are a few synonyms for this tree, including Acer californicum, Acer negundo var. californicum, and Negundo aceroides. The tree is known for its unique bark color, ranging from light green to grayish-brown, as well as its compound leaves and winged fruits. California Box Elders are often found in riparian areas, along streambanks, and in moist woodlands. The tree is a valuable source of food and habitat for wildlife, including birds and mammals.