Cycads /ˈsaɪkædz/ are seed plants that typically have a stout and woody (ligneous) trunk with a crown of large, hard, stiff, evergreen and (usually) pinnate leaves.

[14] The two extant families of cycads all belong to the order Cycadales, and are the Cycadaceae and Zamiaceae (including Stangeriaceae).

Based on genetic studies, cycads are thought to be more closely related to Ginkgo than to other living gymnosperms.

[15][16] Cycads Ginkgo Conifers Bennettitales Gnetales Angiosperms Cycads Ginkgo Conifers Gnetophytes (flowering plants) Cycas Dioon Macrozamia Lepidozamia Encephalartos Bowenia Ceratozamia Stangeria Zamia Microcycas Classification of the Cycadophyta to the rank of family.

[29] Although the Mesozoic is sometimes called the "Age of Cycads," some other groups of extinct seed plants with similar foliage, such as Bennettitales and Nilssoniales, that are not closely related, may have been more abundant.

[18] The living cycads are found across much of the subtropical and tropical parts of the world, with a few in temperate regions such as in Australia.

[citation needed] They are also found in Mexico, the Antilles, southeastern United States, Australia, Melanesia, Micronesia, Japan, China, Southeast Asia, Bangladesh, India, Sri Lanka, Madagascar, and southern and tropical Africa, where at least 65 species occur.

Some can survive in harsh desert or semi-desert climates (xerophytic),[33] others in wet rain forest conditions,[34] and some in both.

[35] Some can grow in sand or even on rock, some in oxygen-poor, swampy, bog-like soils rich in organic material.

[citation needed] Nuts of the Cycas orientis (nyathu) are coveted by the Yolngu in Australia's Arnhem Land as a source of food.

They are harvested on their dry season to leach its poison under water overnight before ground into a paste, wrapped under bark and cooked on open fire until done.

[36] Roots of Zamia integrifolia were used by the Seminole and other native peoples to produce Florida arrowroot by a similar process.

It serves as a powerful taboo sign,[37] and a pair of namele leaves appears on the national flag and coat of arms.