genus of about 18 species of cycads (cycad) in the family Zamiaceae. The species are native to Mexico and Central America and are characterized by cones with scales (sporophylls) that have pairs of spinelike horns. Species are popular in cultivation as ornamentals and specimen plants. However, in nature most of the species are restricted to small geographic areas. Many of the Ceratozamia species are critically endangered, and all are protected by law from unauthorized collection or export.