Hardy Orange, Trifoliate Orange, Poncirus Trifoliata

… almost perfect as a deer barrier hedge planting due to its stature, branch density, beautiful spring flowers and two-inch thorns, however not perfect because the plant is rapidly becoming one of the top non-native invasive plants in the southern states.

Almost natural, because as noted it is a non-native, introduced to the U.S. from China in the 1850s. The cold-hardiness attribute made the Hardy Orange a mainstay as a root stock for citrus production in the U.S.