Cycad << SY kad >> is a large subtropical and tropical seed plant. It is related to conifers (cone-bearing trees), such as the pine and spruce, but looks like a palm or fern. Some cycads have unbranched, erect stems that may be 60 feet (18 meters) high. Others have a partially underground stem, called a tuber, that resembles a potato. Some species reach ages of nearly a thousand years.
The cycad’s leathery, fernlike leaves grow in a circle at the end of the stem. New leaves emerge every year and live several years. The cycad has a strobilus (large cone) that contains seeds. The cone grows erect in the center of the circle of leaves. When the seeds mature, part of the strobilus shrivels, allowing the seeds to drop.
Scientists have found fossils which show that cycads were common during prehistoric times. The cycads are the most primitive seed plants, but not necessarily the most ancient. They grow in only a few small areas. One kind of cycad, called Zamia, is common in tropical America.
