Christmas Cactus, also known as Tsejo, Christmas, Cholla, Pencil-joint Cholla, Holycross Cholla, Diamond Cactus and Darning Needle Cactus, has the slenderest stems of all southwestern chollas, many tangled, spiny branches sprout thin, 1/4-inch stems forming a bush up to 3 feet high in the open, up to 6 feet when growing among desert trees. One long gray or tan spine up to 2 inches long grows from each small cluster of reddish bristles. They bloom in the winter with red blossoms.