Cycadales

(botany) An ancient order of plants in the class Cycadopsida characterized by tuberous or columnar stems that bear a crown of large, usually pinnate leaves.

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.

The cycads, often incorrectly referred to as palms, range from a few inches (Zamia) to 65 ft (20 m; Macrozamia) tall. The stems are cylindrical and often branched; in some the stem is subterranean, in others it is mainly above the ground. The pinnate (or bipinnate in Bowenia) leaves are borne at the apex of the stems. Microsporophylls and megasporophylls are borne in cones of highly varied appearance. Male and female cones appear on separate plants (dioecious). See also Cycadopsida; Pinophyta; Plant kingdom.