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![Pteridospermales (seed ferns),Aiswaria Raj,St.Mary’s College
PENTOXYLALES
The name was proposed by Prof. Birbal Sahini in the year
1948 for a group of fossil plants.
Distribution- Rajmahal hills [Bihar] of India & from New
Zealand.
The order includes - number of stems [Pentoxylon and
Nipanioxylon ], Leaves [Nipaniophyllum].
Pollen bearing organs [ Sahnia ].
Seed bearing organs [ Carnoconites ].](https://image.slidesharecdn.com/aiswariaslideshareppt2-190621042345/75/Botany-Pentoxylales-2-2048.jpg)
![Pteridospermales (seed ferns),Aiswaria Raj,St.Mary’s College
Reproductive organ
The reproductive organs were unisexual. Both the seed bearing
organs [carnoconities] & pollen bearing organs [sahnia] were born
terminally on the dwarf shoots.
Female cones looked like stalked mulberry fruits.
There were no sterile structures similar to magasporophylls.
The ovule is surrounded by single integument that was free from
nucellus.](https://image.slidesharecdn.com/aiswariaslideshareppt2-190621042345/75/Botany-Pentoxylales-8-2048.jpg)
![Pteridospermales (seed ferns),Aiswaria Raj,St.Mary’s College
Interrelationship
Pentoxylales resemble the cycadophytes in their leaf anatomy eg;
the diploxylic bundles & the haplocheilic stomata in leaf.
Pycnoxylic wood resemble conifers.
The pteridospermous family Medullosaceae in having a polystelic
vascular bundle.
Presence of syndeticheilic stomata, in addition to haplocheilic
[cycad character] ones is a bennettitalean character.](https://image.slidesharecdn.com/aiswariaslideshareppt2-190621042345/75/Botany-Pentoxylales-10-2048.jpg)
Uploaded bySt Mary's College,Thrissur,Kerala
Botany:Pentoxylales
The document summarizes the Pentoxylales order of fossil plants. Some key points: - Pentoxylales were first proposed in 1948 and included plant fossils found in India and New Zealand consisting of stems, leaves, pollen organs, and seed organs. - The plants were likely shrubs or small trees with multi-stemmed trunks bearing spirally arranged leaves. - Anatomically, the stems had 5-6 vascular bundles and thick, compact wood resembling conifers. Leaves had two zones of xylem and both syndetocheilic and haplocheilic stomata. - Reproduction involved unisexual cones, with
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Introduction to Pentoxylales, presented by Aiswaria Raj, Assistant Professor at St. Mary’s College, Thrissur.
Proposed by Prof. Birbal Sahini in 1948, includes fossil plants from Rajmahal hills and New Zealand. Key plant components: stems (Pentoxylon, Nipanioxylon), leaves (Nipaniophyllum), and reproductive organs.
Anatomy indicates polystelic stems with multiple primary steles; secondary wood is pycnoxylic but growth rings can't confirm annual nature.
Leaf anatomy features diploxylic condition with two xylem types; stomatal types include syndetocheilic and haplocheilic.
Describes unisexual reproductive organs with seed-bearing and pollen-bearing structures borne terminally on dwarf shoots; notes on ovule integument.
Details about male reproductive structures, including arranged microsporangiophores, unilocular sporangia with boat-shaped pollen grains.
Discusses similarities between Pentoxylales and cycadophytes, conifers, and Medullosaceae, including anatomical features.
Reference for further reading on Gymnosperms by Vasishta et al., published by S. Chand Publications.
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Botany:Pentoxylales
- 1. PENTOXYLALES Aiswaria Raj Assistant Professor Departmentof Botany St. Mary’s College, Thrissur
- 2. Pteridospermales (seed ferns),AiswariaRaj,St.Mary’s College PENTOXYLALES The name was proposed by Prof. Birbal Sahini in the year 1948 for a group of fossil plants. Distribution- Rajmahal hills [Bihar] of India & from New Zealand. The order includes - number of stems [Pentoxylon and Nipanioxylon ], Leaves [Nipaniophyllum]. Pollen bearing organs [ Sahnia ]. Seed bearing organs [ Carnoconites ].
- 3. Pteridospermales (seed ferns),AiswariaRaj,St.Mary’s College MORPHOLOGY The plants were probably shrubs or small trees. The stems were 3 mm to 2 cm long. It bore rhomboidal leaf scars & spirally arranged leaf. The branches were of two types- Long shoots Dwarf shoot
- 4. Pteridospermales (seed ferns),AiswariaRaj,St.Mary’s College
- 5. Pteridospermales (seed ferns),AiswariaRaj,St.Mary’s College ANATOMY The stem were polystelic with 5&6 primary steles hence the name pentoxyleae. Each stele have it’s own cambium, it produced more secondary tissue towards center so that secondary wood became exocentric. The secondary xylem was pycnoxylic, ie; the wood was very compact. The secondary wood shows growth rings but it cannot be definitely stated whether they represent annual rings.
- 6. Pteridospermales (seed ferns),AiswariaRaj,St.Mary’s College
- 7. Pteridospermales (seed ferns),AiswariaRaj,St.Mary’s College In the leaf anatomy it has diploxylic condition ie; two distinct regions of xylem one centripetal & the other is centrifugal. The stomata were regarded by Sahni to be syndetocheilic but later Vishnu Mitter found that haplocheilic or cycadalean stomata also occur. Syndetocheilic-guard cells are surrounded by 2 subsidiary cells. Haplocheilic-guard cells surrounded by 6 or 7 subsidiary cells.
- 8. Pteridospermales (seed ferns),AiswariaRaj,St.Mary’s College Reproductive organ The reproductive organs were unisexual. Both the seed bearing organs [carnoconities] & pollen bearing organs [sahnia] were born terminally on the dwarf shoots. Female cones looked like stalked mulberry fruits. There were no sterile structures similar to magasporophylls. The ovule is surrounded by single integument that was free from nucellus.
- 9. Pteridospermales (seed ferns),AiswariaRaj,St.Mary’s College The male flowers born terminally on short lateral shoots. Each flower consisted of a receptacle. About 24 microsporangiophores were arranged around it in a single whorl. The sporangia is unilocular & contain boat-shaped pollen grains. Each sporangium received a single vascular bundle that divided into several radiating branches.
- 10. Pteridospermales (seed ferns),AiswariaRaj,St.Mary’s College Interrelationship Pentoxylales resemble the cycadophytes in their leaf anatomy eg; the diploxylic bundles & the haplocheilic stomata in leaf. Pycnoxylic wood resemble conifers. The pteridospermous family Medullosaceae in having a polystelic vascular bundle. Presence of syndeticheilic stomata, in addition to haplocheilic [cycad character] ones is a bennettitalean character.
- 11. REFERENCE Vasishta P.C, SinhaA. K., Anil Kumar, Gymnosperms, S. Chand Publications Pteridospermales (seed ferns),Aiswaria Raj,St.Mary’s College