Ceratozamia contains an interesting and diverse group of species. The are found in a wide range of habitats, from the rain forest, cloud forest, dry pine oak forest, to desert, over a wide range of elevations.
Cycas is more widely distributed than any other cycad genera. Species are found in the far east as the Tongo Islands and Fiji, west through New Caledonia, Vanuatu, the Solomon Islands, Australia, New Guinea, the Mariana Islands, the Philippines, the Ryukyu Islands, southern Japan, southern China, Taiwan, Vietnam, Laos, Cambodia, Thailand, Malaysia, Indonesia, Myanmar (Burma), India, Sri Lanka (Ceylon), Madagascar, the Comoro Islands, and along the east coast of Africa, where it was probably introduced by humans.
The conservation status of most species od Dioon is secure. Regeneration by seed and the survival rate of seedlings in most species is very good. The implementation of CITES has stopped the export of dioons from Mexico, but in more recent years, increasing numbers of them have been used in gardening and landscaping within Mexico.
Encephalartos grows in Arica, from desert conditions to savanna and forest, but it appears that no species of Encephalartos occurs in rain forest. Elevational range is from sea level to 8,000 feet at which plants are regularly subjected to snow and freezing. Because of its wide range of leaf forms and colors, Encephalartos has always been sought by botanical gardens and collectors. Almost all species are easy to grow, and growth is rapid if the proper conditions are provided.
Lepidozamia is distributed in Australia, coastal tropical and subtropical Queensland, and northern coastal New South Wales, where it occurs in wet sclerophyll forest or rain forest, from sea level to about 2,000 feet. Both species of the genus Lepidozamia are handsome, hardy to semihardy plants with several attributes recommending them for landscape or garden use. Foremost in this respect are their rapid growth, graceful habit, and complete lack of spines or teeth anywhere on the plants.
Distribution of Macrozamia is in Australia, mainly coastal New South Wales and Queensland. The conservation status of the macrozamias ranges from not threatened to extremely endangered. Some species have a wide distribution coupled with large populations and prolific regenerations, whereas others are restricted in range and are having their remaining habitats cleared for agriculture. The interest in Australian cycads has caused a growing demand for plants, both in Australia and abroad. Collecting of wild plants would ultimately have a devastating effect on the populations of the rarer species. Some growers are starting to produce nursery plants from seed, and it is hoped that this will reduce the numbers of plants removed from habitat.
Zamia is second only to Cycas in the size of its distributional area, and is one of only three cycad genera found on both sides of the equator. Zamia ranges from Georgia and Florida, south through Mexico, the West Indies, and Central America into South America as far south as northern Chile, Bolivia, and Brazil.