Leaf Summary


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Leaf Summary

  1. 1. • A leaf is an organ of a vascular plant, as defined in botanical terms, and in particular in plant morphology. Foliage is a mass noun that refers to leaves as a feature of plants. • Typically a leaf is a thin, flattened organ borne above ground and specialized for photosynthesis.
  2. 2. • Leaves are the powerhouse of plants. In most plants, leaves are the major site of food production for the plant. • Sometimes leaves are divided into two or more sections called leaflets. – Leaves with a single undivided blade are called simple, those with two or more leaflets are called compound.
  3. 3. oLower epidermis – outmost tissue on the lower side of the leaf; protects the leaf oUpper epidermis – outmost tissue on the upper side of the leaf; protects the leaf oMesophyll – all of the middle tissue of the leaf  Palisade layer  Spongy layer
  4. 4. o Vascular Bundles – supply support for the leaf; contain the xylem and the phloem  Xylem – found in the vein; transports minerals and water from roots to shoots  Phloem – found in the vein; transports sugar & other products of photosynthesis from leaves to other parts of the plant
  5. 5. • Cuticle – Waxy substance that covers the leaves & stems – Waterproof layer that keeps water in plants • Stomata - opening between the guard cells; allows for gas exchange and some water  Guard cells - specialized cells surround the stomata and are shaped like two cupped hands.
  6. 6. • External Anatomy o Petiole – a thin stalk that connects the blade of the leaf to the plant’s stem o Blade – a thin flat part; extends of the end of the petiole o Midrib – main vein; continuation of petiole o Leaf tip- leaf apex of the outer end of the leaf o Leaf Base – expanded area where leaf attached
  7. 7. • Simple leaf = undivided blade with a single axillary bud at the base of its petiole.
  8. 8. • Compound leaf = blade divided into leaflets, leaflets lack an axillary bud but each compound leaf has a single bud at the base of its petiole
  9. 9. • Palmately Compound - is one in which all the leaflets arise from a common point at the tip of the petiole. • Pinnately Compound - a row of leaflets forms on either side of an extension of the petiole called the rachis
  10. 10. • Opposite – A pair of leaves is attached at a node. They are at the same level(node) • Alternate – A single leaf is attached at a node. They are the different level(node) • Whorled – Three of more leaves are attached at a node.
  11. 11. acicular hastate falcate obovate
  12. 12. • Crenate – If a leaf has a Crenate margin, then the edge of the leaf has blunt, rounded teeth. • Entire – A leaf that is smooth all the way around has an Entire margin
  13. 13. • Serrate – A Serrate margin is when a leaf has sharp, "saw-like" teeth. • Dentate – A Dentate margin is when a leaf has triangular, "tooth- like" edges.
  14. 14. • Incised – If a leaf has an Incised margin, it has deep, irregular teeth. • Lobed – When a leaf has a Lobed margin, the leaf has deep, rounded edges.
  15. 15. • Sinuate – A Sinuate margin describes the sinuous, slightly wavy line along the edge of a leaf. • Undulate – When a leaf has an Undulate margin, it has extremely wavy lines along the edge.
  16. 16. • Denticulate – With fine dentition • Ciliate – With fine hairs
  17. 17. • Acute -Ending in a sharp, but not prolonged point • Acuminate -Long-pointed, prolonged into a narrow, tapering point in a concave manner
  18. 18. • Cuspidate -With a sharp, elongated, rigid tip; tipped with a cusp • Emarginate -Indented,with a shallow notch at the tip
  19. 19. • Aristate -having an awn. • Mucronate -ending in a mucro or sharp point.
  20. 20. • Obtuse -not sharp or pointed; blunt. • Truncate - having a square or broad end.
  21. 21. • Acuminate -Gradually narrowing at the base. • Acute -Becoming Gradually Pointed • Rounded -A curved base with margins that form a smooth arc.
  22. 22. • Oblique -an asymmetrical base with unequal size lobes, attached to the midvein at different levels. • Cordate -is a heart-shaped. • Sagittate -a base with pointed lobes directed downwards.
  23. 23. • Hastate -a base with pointed lobes directed outwards. • Truncate -a broad straight base, abruptly ending at right angles to the midvein