Lycium cooperi is a species of flowering plant in the nightshade family known by the common name peach thorn. It is native to the southwestern United States, where it grows in a variety of desert and mountain habitat types. This is a bushy, erect shrub approaching a maximum height of 4 meters with many rigid, thorny branches. The branches are lined thickly with fleshy oval or widely lance-shaped leaves each 1 to 3 centimeters long and coated with hairy hairs. The flower cluster is a small cluster of tubular flowers roughly 1 to 2 centimeters long including the calyx of fleshy sepals at the base. The flower is white or greenish with lavender or green veining. The corolla is a tube opening into a face with four or five lobes. The fruit is a yellow or orange berry under a centimeter wide containing many seeds.