Bennettitales

bennettitales

1. Bennettitales Presented by : Patel Vanita l M.sc S em : 1 CBO: 402

2. Contents What is Bennettitales ? Classification Bennettitaceae family Williamsoniaceae family

3. What is Bennettitales ? This group of fossil plants flourished well during the Triassic to lower Cretaceous periods of Mesozoic era. As the Carboniferous period is called the "Ages of ferns " the Mesozoic era is called the "Ages of cycads. "

4. History The name " Bennettitales " has been given to honor J. J Bennett an English botanist. The fossilized trunks of genus Bucklandia was the first specimen of Bennettitales collected from Great Britain in 1825.

5. Classification Walton ( 1940 ) recognized following two families in Bennettitales. Bennettitaceae Williamsoniaceae

6. Bennettiteae : Flower deeply sunk among the persistent leaf bases and were present on short thick trunks. Example : Cycadeoidea 2 . Willamsonieae : flower fully exposed and present on slender stems. Example : williamsoniella

7. Bennettitaceae Anatomy : The unique trunks have been nicely illustrated by wieland in his book 'American fossils Cyads ' and by ward in his book 'status of the Mesozoic flora. '

8. Microsporophyll or Androecium The tip the microsporophyll was fused to its base. The distal part of each microsporophyll was parenchymatous with no indications of fusion or canals. Each pollen capsule or synangium measures 3.5 *2.5 millimeters and contained a varying number of pollen sacs or micro sporangia.

9. The number is stated to very between 20 to 30 per synangium and are separated by distinct walls. The synangium has a several layered thick wall. The outer layer is composed of palisade like cells that have thick walls.

10. Gynoceium The young nucleolus is made up of thin walled cells those at the chalazal and being much smaller than those at the microsporpylar end. The cells in the micropylar region are much elongated and are up to 80 u long. A single cells with a pointed tip appears development. The cells at the chalazal end are smaller.

11. Williamsoniaceae Anatomy : The primary vasculature consisted of a ring of endarch conjoint and collateral vascular bundles. The pith extended between the vascular bundles in the from of pith rays. The secondary wood formed an extensive cylinder around the primary xylem .

12. Reproduction Female flower : The tip of the receptacle was naked. The ovule had short stalks that bear the body of the ovule which consisted of a single integument surrounding the nucleolus. The nucleolus had a prominent beak and a pollen chamber.

13. Male flower : The pinnae were almost opposite and slightly tapered out wards. The proximal petiole like portion bore numerous globose pollen containing bodies. These leaf like bodies contained Syndetocheilic stomata that are characteristic of Bennettitales.

14. Reference Botany for degree students Gymnosperms by - P.C.VASISHTA - A.K.SINHA - ANIL KUMAR https://en.m.Wikipedia.org

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