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Angiosperms V Primary Growth: Leaves

Angiosperms V Primary Growth: Leaves. Leaf Morphology. Leaves are arranged on stems in either an opposite , alternate , or whorled pattern This arrangement is called the phyllotaxis Most leaves are either simple or compound. A SIMPLE LEAF. base. petiole. venation. margin. apex.

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Angiosperms V Primary Growth: Leaves

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  1. Angiosperms VPrimary Growth: Leaves

  2. Leaf Morphology • Leaves are arranged on stems in either an opposite, alternate, or whorled pattern • This arrangement is called the phyllotaxis • Most leaves are either simple or compound A SIMPLE LEAF

  3. base petiole venation margin apex External Leaf Morphology • The leaf blade is connected to the stem by the petiole • Other leaf parts include: base, margin, apex, venation

  4. Simple Leaves

  5. Compound Leaves • Pinnately compound leaves are similar to ferns: leaflets attached along a rachis • Palmate leaves have leaflets attached at one point

  6. Simple vs. Compound Leaves • Axillary buds occur at the base of each leaf - not at the base of leaflets • The abscission layer forms at the base of the leaf’s petiole - not at the base of a leaflet • Leaflets are generally all produced in the same plane - leaves have a phyllotaxis

  7. Internal Structure (eudicot)

  8. Internal Structure (monocot) • Upper epidermis • Bulliform cells • Mesophyll • Veins with bundle sheath cells • Guard cells

  9. Action of Bulliform Cells (open)

  10. Action of Bulliform Cells (closed)

  11. Leaf Abscission • Abscission takes place at the base of the leaf (not leaflets) • Response to hormones triggered by environment changes • Two regions: • Separation layer • Protective layer

  12. Variations and Uses • Multiple epidermal layers • Thick cuticles • Many trichomes (African violet) • Stomata in sunken pits with trichomes (xerophytes) • Stomata only on the upper surface(water lilies) • Leaves modified to be tendrils or spines

  13. Variations and Uses (cont.) • Carnivorous plants (specialized for obtaining mineral nutrients in wet or mineral poor habitats) • Venus fly trap • Sundew • Pitcher plants

  14. Sundew

  15. Pitcher Plants

  16. Variations andUses (cont.) • Leaves for human consumption or use as medicines, dyes, fibers, waxes and for smoking

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