FIG. 33.15 Cycads. (a) Most living cycads have thick, unbranched stems that support large leaves and cones. Shown here is Encephalartos friderici-guilielmi. (b) Many cycads, such as Encephalartos transvenosus, have large cones. (c) Mature seeds are large (here are shown those of Cycas circinalis) and contain a relatively large female gametophyte that provides nutrition for the embryo and germinating sporophyte.