Cycadophyta
The Cycadophytes are a junction of plant Gymnosperme S appeared with the Permien which currently count 360 species approximately gathered in the order of the Cycadales and in the class of the Cycadopsida. The order of the Cycadales was described by Barthélemy Charles Joseph Dumortier (1797-1878).
Description
Cycadales are plants of rather big size to the aspect close to that of the Palmier S. the cycadales like the pinophyte S and contrary to the palm trees present a secondary growth in thickness starting from a sapwood. This growth is slow.The reproductive structures are cones around the apex of the plant. The cycadales are dioïques; i.e. there exist seedlings carrying only male cones and others only of the cones females.
As at the ginkgo the maturation of the male gamétophytes (germination of the grains of pollen) releases from the Anthérozoïde S ciliés (or Spermatozoïde S) although it is a pollen tube which brings them in contact with the oosphere.
Classification
- class Cycadopsida
- order Cycadales
- family Cycadaceae
- family Stangeriaceae
- family Zamiaceae
References
External bonds
- royal Botanical garden of Sydney
- Photographs of Cycadales
| Random links: | Kubaba | British tournament of Rugby at XV 1904 | Barracks of the Praetorian Guard | Alastaro | Whimsical Cosmonauts | Snowdrop |