[4][5] As of April 2024, there are 119 accepted species within the genus Cycas, all of which are native to Asia, Oceania, and eastern Africa and the Indian ocean region, with the largest number of species native to Australia, China and Vietnam.

Within Asia, Cycas species are native from India and Sri Lanka in the west, through China to Japan in the north east and through south east Asia (including the Philippines) to Indonesia in the south.

C. thouarsii grows in a comparatively wide area including coastal regions of Mozambique, Tanzania, and Kenya in mainland Africa, extending to the Seychelles, Madagascar and Comoros islands in the Indian Ocean.

[8][12] In Oceania, Cycas species are native to Australia, Papua New Guinea, and the island nations of the Pacific Ocean region, but are absent from New Zealand.

[18] The earliest fossils assignable to Cycas are known from the Paleogene of East Asia, such as Cycas fushunensis from the Eocene (around 47.5 million years ago) of Northeast China with East Asia likely representing the ancestral homeland of the genus.

[8] Fossil seeds from the Middle Jurassic of England and British Columbia were suggested in a 2017 study to be more closely related to Cycas than other cycads and were assigned to the same family, Cycadaceae.

[21] The leaf fossil genus Paracycas known from the Jurassic and Cretaceous of Europe has been suggested to be early representatives of the Cycas lineage by cladistic analysis.

[18] The plants are dioecious, and the family Cycadaceae is unique among the cycads in not forming seed cones on female plants, but rather a group of leaf-like structures called megasporophylls each with seeds on the lower margins, and pollen cones or strobilus on male individuals.

The foliage leaves are pinnate (or more rarely bipinnate) and arranged spirally, with thick and hard keratinose.

K.D.Hill C. debaoensis Y.C.Zhong & C.J.Chen C. brachycantha K.D.Hill, H.T.Nguyen & P.K.Lôc C. immersa Craib C. bifida (Dyer) K.D.Hill C. szechuanensis W.C.Cheng & L.K.Fu C. wadei Merr.

C. nongnoochiae K.D.Hill C. elongata (Leandri) D.Y.Wang C. tansachana K.D.Hill & S.L.Yang C. lindstromii S.L.Yang, K.D.Hill & Nguyên C. condaoensis K.D.Hill & S.L.Yang C. chamaoensis K.D.Hill C. media R.Br.

C. segmentifida D.Y.Wang & C.Y.Deng C. dolichophylla K.D.Hill, H.T.Nguyen & P.K.Lôc C. simplicipinna (Smitinand) K.D.Hill C. guizhouensis K.M.Lan & R.F.Zou C. chevalieri Leandri C. maconochiei Chirgwin & K.D.Hill C. arenicola K.D.Hill C. schumanniana Lauterb.

C. aculeata K.D.Hill & H.T.Nguyen C. silvestris K.D.Hill C. basaltica C.A.Gardner C. semota K.D.Hill C. orientis K.D.Hill C. canalis K.D.Hill C. hongheensis S.Y.Yang & S.L.Yang C. conferta Chirgwin C. angulata R.Br.