 |
| The Cycad Pages
| |
FAMILY
Zamiaceae
|
|
Palm like plants with subterranean to tall and erect usually unbranched
cylindrical stems, stems clad with persistent leaf bases (in Australian
genera). Leaves simply pinnate, spirally arranged, interspersed with
cataphylls; leaflets sometimes dichotomously divided. Longitudinal
ptyxis erect to inflexed or sometimes reflexed, horizontal ptyxis
conduplicate. Leaflets with several sub parallel dichotomously
branching longitudinal veins, lacking a mid rib; stomata on both
surfaces or undersurface only; individual ptyxis flat. Trichomes
coloured or transparent, branched or unbranched, short curved or
idioblastic. Male and female sporophylls spirally aggregated into
determinate axillary cones. Female sporophylls simple, appearing
peltate, with a barren stipe and an expanded and thickened lamina
with 2 (rarely 3 or more) sessile, orthotropous ovules inserted on
the inner (axis facing) surface and directed inwards ("inverted").
Seeds radiospermic.
Two subfamilies with nine genera and about 150 species in the tropical
and warm temperate regions of Africa, Australia and North and South
America. One subfamily, the Encephalartoideae, characterised by
spirally arranged sporophylls (rather than spirally orthostichous),
non articulate leaflets and persistent leaf bases, is represented
in Australia, with two genera and 40 species.
Bowenia
Ceratozamia
Chigua
Dioon
Encephalartos
Lepidozamia
Macrozamia
Microcycas
Zamia
