Poinsettias (Euphorbia pulcherrima) are subtropical plants which originated in Mexico and Guatemala. In their native climate, poinsettias are small woody shrubs that may reach a height of over 10 feet. In the U.S. poinsettias are grown as indoor potted plants popular at Christmas time. While the showy bracts are suggestive of flower petals, they are really modified leaves. The actual poinsettia flowers are less conspicuous by comparison, forming a yellow to red cluster in the center of the bracts.