Zamiaceae
Encyclopedia
The Zamiaceae are a family of cycad
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 warm temperate regions of Africa
, Australia
and North
and South America
.
The Zamiaceae are perennial
, evergreen, and dioecious
. They have subterranean to tall and erect, usually unbranched, cylindrical stems, and stems clad with persistent leaf bases (in Australian genera).
Their leaves
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 occur either on both surfaces or undersurface only.
Their roots have small secondary roots. The coral-like roots develop at the base of the stem at or below the soil
surface.
Male and female sporophyll
s are spirally aggregated into determinate cones
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
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
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
ous, producing poisonous glycoside
s known as cycasins.
Some classifications also place the genus Bowenia
in the Zamiaceae.
Cycad
Cycads are seed plants typically characterized by a stout and woody trunk with a crown of large, hard and stiff, evergreen leaves. They usually have pinnate leaves. The individual plants are either all male or all female . Cycads vary in size from having a trunk that is only a few centimeters...
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 warm temperate regions of Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
, Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
and North
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
and South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
.
The Zamiaceae are perennial
Perennial plant
A perennial plant or simply perennial is a plant that lives for more than two years. The term is often used to differentiate a plant from shorter lived annuals and biennials. The term is sometimes misused by commercial gardeners or horticulturalists to describe only herbaceous perennials...
, evergreen, and dioecious
Dioecious
Dioecy is the property of a group of biological organisms that have males and females, but not members that have organs of both sexes at the same time. I.e., those whose individual members can usually produce only one type of gamete; each individual organism is thus distinctly female or male...
. They have subterranean to tall and erect, usually unbranched, cylindrical stems, and stems clad with persistent leaf bases (in Australian genera).
Their leaves
Leaf
A leaf is an organ of a vascular plant, as defined in botanical terms, and in particular in plant morphology. Foliage is a mass noun that refers to leaves as a feature of plants....
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 occur either on both surfaces or undersurface only.
Their roots have small secondary roots. The coral-like roots develop at the base of the stem at or below the soil
Soil
Soil is a natural body consisting of layers of mineral constituents of variable thicknesses, which differ from the parent materials in their morphological, physical, chemical, and mineralogical characteristics...
surface.
Male and female sporophyll
Sporophyll
A sporophyll is a leaf that bears sporangia. Both microphylls and megaphylls can be sporophylls. In heterosporous plants, sporophylls bear either megasporangia , or microsporangia...
s are spirally aggregated into determinate cones
Conifer cone
A cone is an organ on plants in the division Pinophyta that contains the reproductive structures. The familiar woody cone is the female cone, which produces seeds. The male cones, which produce pollen, are usually herbaceous and much less conspicuous even at full maturity...
that grow along the axis. Female sporophylls are simple, appearing peltate, with a barren stipe
Stipe (botany)
In botany, a stipe is a stalk that supports some other structure. The precise meaning is different depending on which taxonomic group is being described....
and an expanded and thickened lamina with 2 (rarely 3 or more) sessile ovule
Ovule
Ovule means "small egg". 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 , and the megaspore-derived female gametophyte in its center...
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
Cotyledon
A cotyledon , is a significant part of the embryo within the seed of a plant. Upon germination, the cotyledon may become the embryonic first leaves of a seedling. The number of cotyledons present is one characteristic used by botanists to classify the flowering plants...
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
Poison
In the context of biology, poisons are substances that can cause disturbances to organisms, usually by chemical reaction or other activity on the molecular scale, when a sufficient quantity is absorbed by an organism....
ous, producing poisonous glycoside
Glycoside
In chemistry, a glycoside is a molecule in which a sugar is bound to a non-carbohydrate moiety, usually a small organic molecule. Glycosides play numerous important roles in living organisms. Many plants store chemicals in the form of inactive glycosides. These can be activated by enzyme...
s known as cycasins.
Genera
- Subfamily Encephalartoideae
- Tribe Diooeae
- DioonDioonDioon is a genus of cycads in the family Zamiaceae. It contains 11 accepted species that are native to Mexico, Honduras, and Nicaragua. Their habitats include tropical forests, pine-oak forest, and dry hillsides, canyons and coastal dunes....
Lindl.John LindleyJohn Lindley FRS was an English botanist, gardener and orchidologist.-Early years:Born in Catton, near Norwich, England, John Lindley was one of four children of George and Mary Lindley. George Lindley was a nurseryman and pomologist and ran a commercial nursery garden...
- Dioon
- Tribe Encephalarteae
- Subtribe Encephalartinae
- EncephalartosEncephalartosEncephalartos is a genus of cycad native to Africa. Several species of Encephalartos are commonly referred to as bread palms, bread tree or Kaffir bread since a bread-like starchy food can be prepared from the centre of the stem. All the species of Encephalartos are endangered...
Lehm.Johann Georg Christian LehmannJohann Georg Christian Lehmann was a German botanist.Born at Haselau, near Uetersen, Holstein, Lehmann studied medicine in Copenhagen and Göttingen, obtained a doctorate in medicine in 1813 and a doctorate in philosophy from he University of Jena in 1814...
- Encephalartos
- Subtribe Macrozamiinae
- MacrozamiaMacrozamiaMacrozamia is a genus of 38-40 species of cycads, in the family Zamiaceae, endemic to Australia. The majority of the species occur in eastern Australia in southeast Queensland and New South Wales, with one species in the Macdonnell Ranges of Northern Territory and three in southern Western...
Miq.Friedrich Anton Wilhelm MiquelFriedrich Anton Wilhelm Miquel was a Dutch botanist.He was head of the botanical gardens at Rotterdam , Amsterdam and Utrecht . He directed the Rijksherbarium at Leiden from 1862... - LepidozamiaLepidozamiaLepidozamia is a genus of two species of cycad, native to Australia. The name, derived from the Greek word lepidos, meaning scaly, refers to the scale-like structure of the stem and leaf bases. They are native to rainforest climates in eastern Queensland and eastern New South Wales...
Lehm.
- Macrozamia
- Subtribe Encephalartinae
- Tribe Diooeae
- Subfamily Zamioideae
- Tribe Ceratozamieae
- CeratozamiaCeratozamiaCeratozamia is a genus of New World cycads in the family Zamiaceae. The genus contains 16-18 currently living species and one or two fossil species. Most species are endemic to mountainous areas of Mexico, while C. robusta extends into the mountains of Guatemala and Belize...
Brongn.Adolphe Theodore BrongniartAdolphe-Théodore Brongniart was a French botanist. He was the son of the geologist Alexandre Brongniart and grandson of the architect, Alexandre-Théodore Brongniart. Brongniart's pioneering work on the relationships between extinct and existing plants has earned him the title of father of...
- Ceratozamia
- Tribe Zamieae
- Subtribe Microcycadinae
- MicrocycasMicrocycasMicrocycas is a genus of cycads in the family Zamiaceae containing only one species, Microcycas calocoma, endemic to a small area in western Cuba in Pinar del Río Province....
(Miq.Friedrich Anton Wilhelm MiquelFriedrich Anton Wilhelm Miquel was a Dutch botanist.He was head of the botanical gardens at Rotterdam , Amsterdam and Utrecht . He directed the Rijksherbarium at Leiden from 1862...
) A.DC.
- Microcycas
- Subtribe Zamiinae
- ChiguaChiguaChigua is a genus of cycads in the family Zamiaceae containing two species, endemic to small areas in northwestern Colombia. Described by botanist Dennis Stevenson in 1990, it is the most recently named genus. Both species are listed as Critically Endangered by the IUCN Red List...
D.W.Stev. - ZamiaZamiaZamia is a genus of cycad of the family Zamiaceae, containing around 50 species, native to North, Central and South America. Species occur as far north as Georgia in the United States to as far south as Bolivia Zamia is a genus of cycad of the family Zamiaceae, containing around 50 species, native...
L.
- Chigua
- Subtribe Microcycadinae
- Tribe Ceratozamieae
Some classifications also place the genus Bowenia
Bowenia
The genus Bowenia, includes two living and two fossil species of cycads in the family Stangeriaceae, sometimes placed on their own family Boweniaceae. They are entirely restricted to Australia...
in the Zamiaceae.