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 Encephalartos lebomboensis
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The Zamiaceae are a family of cycads 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 sporophylls 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 ovules 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 cotyledons.
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.
Genera
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- Subfamily Encephalartoideae
- Chigua
- Dioon
- Encephalartos, including the Modjadji cycad
- Lepidozamia
- Subfamily Zamioideae
- Macrozamia
- Ceratozamia
- Microcycas
- Zamia
Some classifications also place the genus Bowenia in the Zamiaceae.
As with all cycads, members of the Zamiaceae are poisonous, producing poisonous glycosides known as cycasins.
.JPG) Dioon mejiae |
References
- The Cycad Pages: Zamiaceae
- Flora of North America
- New York Botanical Garden: Vascular Plant Type Catalog, some Zamiaceae genera and species.
Wikipedia content modification information:
- This page was last modified on 10 April 2008, at 04:21.
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