An order of the class Cycadopsida of the division Pinophyta (gymnosperms) consisting of four families, Cycadaceae, Stangeriaceae, Zamiaceae, and Boweniaceae, with perhaps 100 species. The order dates from the upper Carboniferous and has few living representatives. The cycads were distributed worldwide in the Mesozoic, but today are restricted to subtropical and tropical regions, with the plants occurring in small colonies; few have broad distributions.