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Stems - I

Stems - I. Primary Structure of Stems. Dermal – Epidermis Ground Tissue Cortex Pith Other Vascular Tissue – vascular bundles Collateral VB Bicollateral VB Concentric VB. Acorus stem with endodermis. Amphivasal VB. Morphological concepts used to explain primary anatomy. Stelar Theory

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Stems - I

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  1. Stems - I

  2. Primary Structure of Stems • Dermal – Epidermis • Ground Tissue • Cortex • Pith • Other • Vascular Tissue – vascular bundles • Collateral VB • Bicollateral VB • Concentric VB

  3. Acorus stem with endodermis

  4. Amphivasal VB

  5. Morphological concepts used to explain primary anatomy • Stelar Theory • Leaf Trace Theory

  6. Types of steles Protosteles --------------> Siphonosteles-------------->

  7. Protosteles have a central core of vascular tissue surrounded by cortex (not shown) Xylem Phloem

  8. Haplostele in Psilotum rhizome

  9. Haplostele in Selaginella root

  10. Actinostele in Psilotum stem

  11. Actinostele in Ranunculus root

  12. Plectosteles in Lycopodium stems

  13. Siphonosteles have a central pith surrounded by a cylinder of vascular tissue Ectophloic Siphonostele Amphiphloic siphonostele Dictyostele

  14. Ectophloic siphonstele in fern rhizome with a ring of xylem surrounded by a ring of phloem

  15. Amphiphloic siphonostele in a fern rhizome with two rings of phloem on each side of xylem

  16. Leaf traces and leaf gaps

  17. Siphonostele with a leaf gap and leaf trace

  18. Dictyosteles are considered amphiphloic siphonosteles with overlapping leaf gaps

  19. Modified siphonosteles

  20. Eustele Dicots and gymnosperms Monocots

  21. Evolution of stelar types

  22. Flattened protostele in Selaginella stem Flattened haplostele? OR Actinostele with two arms?

  23. Actinostele with irregular shape Or a plectostele with connections between xylem areas?

  24. Stele in stem Asteroxylon(fossil member of Division Lycophyta)

  25. Leaf traces originate at the apical meristem

  26. Leaf traces

  27. Anatomy of nodes Unilacunar with 2 traces Unilacunar with 1 trace Multilacunar with many gaps and many traces Trilacunar with 3 traces

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