Pentoxylales

Pentoxylales:-

Characters of Pentoxylales:-

1. Extinct Mesozoic plants found in Jurassic period.

2. Although the exact habit of these plants is not clearly established, these were probably shrubs or very small trees.

3. Long and short shoots were present on these plants.

4. Short shoots had spirally arranged leaves and terminally located reproductive organs.

5. Leaves were thick, simple, lanceolate, and had diploxylic leaf trace.

6. Stomata were formerly thought to be syndetocheilic, but now they are considered to be haplocheilic.

7. Leaves possessed open venation.

8. Stems were polystelic. Basinger et al. (1974) opined that “it may be more appropriate to call each stele as vascular segment or sympodium”.

9. Wood of Pentoxylon was pycnoxylic and resembled Araucaria.

10. Ovules were sessile.

11. Female reproductive organs were like stalked mulberry, consisting of about 20 sessile seeds attached to central receptacle and surrounded by stony layer and then fleshy outer layer of integument uniting them.

12. Male reproductive organs or microsporophyll’s form whorl of branched micro-sporangiophores.

13. The micro-sporangiophores were fused basally into a disc-like structure.

Stem Genera of Pentoxylales:-

1. Pentoxylon Sahnii:-

> Pentoxylon sahnii and Nipanioxylon guptai are the stem genera of “Pentoxyleae”. The stems of Pentoxylon sahnii attained a diameter from 3mm to 2 cm. The stem has always been reported in association with the leaves called Nipaniophyllum.

2. Nipanioxylon:-

> This stem genus of Pentoxyleae was discovered from the village Nipania and hence named Nipanioxylon. Village Nipania is in Rajmahal Hills, near Dumarchir in the Amrapara district (Santhal Parganas) in Bihar (India).