The Zamiaceae are a family of

cycad Cycads are seed plants that typically have a stout and woody (ligneous) trunk (botany), trunk with a crown (botany), crown of large, hard, stiff, evergreen and (usually) pinnate leaves. The species are dioecious, that is, individual plants o ...

s that are superficially palm or fern-like. They are divided into two subfamilies with eight genera and about 150 species in the tropical and subtropical regions of

Africa Africa is the world's second-largest and second-most populous continent after Asia. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 20% of Earth's land area and 6% of its total surfac ...

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

and

North North is one of the four compass points or cardinal directions. It is the opposite of south and is perpendicular to east and west. ''North'' is a noun, adjective, or adverb indicating Direction (geometry), direction or geography. Etymology T ...

and

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...

. The Zamiaceae, sometimes known as zamiads, are

perennial In horticulture, the term perennial ('' per-'' + '' -ennial'', "through the year") is used to differentiate a plant from shorter-lived annuals and biennials. It has thus been defined as a plant that lives more than 2 years. The term is also ...

, evergreen, and

dioecious Dioecy ( ; ; adj. dioecious, ) is a characteristic of certain species that have distinct unisexual individuals, each producing either male or female gametes, either directly (in animals) or indirectly (in seed plants). Dioecious reproduction is ...

. They have subterranean to tall and erect, usually unbranched, cylindrical stems, and stems clad with persistent leaf bases (in Australian genera). Their

leaves A leaf (: leaves) is a principal appendage of the stem of a vascular plant, usually borne laterally above ground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, stem, ...

are simply pinnate, spirally arranged, and interspersed with cataphylls. The leaflets are sometimes dichotomously divided. The leaflets occur with several sub-parallel, dichotomously branching longitudinal veins; they lack a mid rib.

Stomata In botany, a stoma (: stomata, from Greek ''στόμα'', "mouth"), also called a stomate (: stomates), is a pore found in the epidermis of leaves, stems, and other organs, that controls the rate of gas exchange between the internal air spa ...

occur either on both surfaces or undersurface only. Their roots have small secondary roots. The coralloid roots develop at the base of the stem at or below the

soil Soil, also commonly referred to as earth, is a mixture of organic matter, minerals, gases, water, and organisms that together support the life of plants and soil organisms. Some scientific definitions distinguish dirt from ''soil'' by re ...

surface. Male and female sporophylls are spirally aggregated into determinate

cones In geometry, a cone is a three-dimensional figure that tapers smoothly from a flat base (typically a circle) to a point not contained in the base, called the ''apex'' or '' vertex''. A cone is formed by a set of line segments, half-lines, ...

that grow along the axis. Female sporophylls are simple, appearing peltate, with a barren stipe and an expanded and thickened lamina with 2 (rarely 3 or more) sessile

ovule In seed plants, the ovule is the structure that gives rise to and contains the female reproductive cells. It consists of three parts: the ''integument'', forming its outer layer, the ''nucellus'' (or remnant of the sporangium, megasporangium), ...

s inserted on the inner (axis facing) surface and directed inward. The seeds are angular, with the inner coat hardened and the outer coat fleshy. They are often brightly colored, with 2

cotyledon A cotyledon ( ; ; "a cavity, small cup, any cup-shaped hollow", gen. (), ) is a "seed leaf" – a significant part of the embryo within the seed of a plant – and is formally defined as "the embryonic leaf in seed-bearing plants, one or mor ...

s. One subfamily, the Encephalartoideae, is characterized by spirally arranged sporophylls (rather than spirally orthostichous), non-articulate leaflets and persistent leaf bases. It is represented in Australia, with two genera and 40 species. As with all cycads, members of the ''Zamiaceae'' are

poison A poison is any chemical substance that is harmful or lethal to living organisms. The term is used in a wide range of scientific fields and industries, where it is often specifically defined. It may also be applied colloquially or figurati ...

ous, producing poisonous

glycoside In chemistry, a glycoside is a molecule in which a sugar is bound to another functional group via a glycosidic bond. Glycosides play numerous important roles in living organisms. Many plants store chemicals in the form of inactive glycosides. ...

s known as cycasins. The former family Stangeriaceae (which contained ''

Bowenia The genus ''Bowenia'' includes two extant taxa, living and two fossil species of cycads in the family Stangeriaceae, sometimes placed in their own family Boweniaceae. They are entirely restricted to Australia. Description The chromosome count i ...

'' and '' Stangeria'') has been shown to be nested within Zamiaceae by phylogenetic analysis. The family first began to diversify during the

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...

period.

Genera

* '' Dioon'' (14 species) * '' Macrozamia'' (42 species) * '' Lepidozamia'' (2 species) * ''

Encephalartos ''Encephalartos'' is a genus of cycad native to Africa. Several species of ''Encephalartos'' are commonly referred to as bread trees, bread palms or kaffir bread, since a bread-like starchy food can be prepared from the centre of the stem. The ge ...

'' (66 species) * ''

'' Hook. ex Hook.f. (2 extant species) * '' Ceratozamia'' (27 species) * '' Stangeria'' T.Moore (1 species) * '' Zamia'' (76 species) * '' Microcycas'' (1 species) * †'' Eostangeria'' (3 species, Cenozoic, Europe, North America) * †'' Eobowenia'' (1 species, Early Cretaceous, Argentina) * †'' Wintucycas'' (2 species, Late Cretaceous-Paleocene, Argentina) * †'' Restrepophyllum'' (1 species, Early Cretaceous, Argentina) * †'' Skyttegaardia'' (2 species Early Cretaceous, Denmark, Late Cretaceous, United States)

Gallery

File:Dioon edule03.jpg, '' Dioon edule'' File:Dioon mejae.jpg, '' Dioon mejiae'' File:E.altensteinii kg 011.jpg, '' Encephalartos altensteinii'' File:Encephalartos lebomboensis - Lebombo cycad - desc-fruiting stalk.jpg, '' Encephalartos lebomboensis'' File:Lepidozamia peroffskyana at Kerikeri, Bay of Islands, New Zealand.jpg, '' Lepidozamia peroffskyana'' File:Macrozemia moorei.jpg, '' Macrozamia moorei'' File:Ceratozamia Hildae Leave.jpg, '' Ceratozamia hildae'' File:Microcycas calocoma01.jpg, '' Microcycas calocoma'' File:Zamia furfuracea04.jpg , '' Zamia furfuracea''

References

The Cycad Pages: ZamiaceaeFlora of North America
* {{Authority control Cycads Plant families