Cycads are a kind of tree plants living in hot countries. The sporangial leaves evoking the vegetative leaves, several traits of gigantism – very large leaves, large diameter of the trunks, ovules as big as pigeon eggs, antherozoids (spermatozoa) perceptible to the naked eye … – are marks of age of a group almost extinct.

105 species are identified in East Africa, Madagascar, Southeast Asia, New Caledonia and Tonga. The best known species is Cycas revoluta.