Leaf Summary
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Leaves are thin, flattened organs on plants specialized for photosynthesis. They come in two forms: simple leaves with a single undivided blade, and compound leaves divided into leaflets. Leaves have distinct external and internal structures, including an upper and lower epidermis, mesophyll tissue, vascular bundles, stomata, a petiole, and blade. Their shape, margin, base, and tip can be described using specific botanical terms to characterize their morphology. Leaves are key sites of photosynthesis and food production for plants.
Leaf Summary
- 3. • 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.
- 4. • 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.
- 6. 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
- 7. 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
- 8. • 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.
- 10. • 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
- 11. • Simple leaf = undivided blade with a single axillary bud at the base of its petiole.
- 12. • 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
- 13. • 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
- 14. • 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.
- 17. • 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
- 18. • 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.
- 19. • 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.
- 20. • 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.
- 21. • Denticulate – With fine dentition • Ciliate – With fine hairs
- 22. • Acute -Ending in a sharp, but not prolonged point • Acuminate -Long-pointed, prolonged into a narrow, tapering point in a concave manner
- 23. • Cuspidate -With a sharp, elongated, rigid tip; tipped with a cusp • Emarginate -Indented,with a shallow notch at the tip
- 24. • Aristate -having an awn. • Mucronate -ending in a mucro or sharp point.
- 25. • Obtuse -not sharp or pointed; blunt. • Truncate - having a square or broad end.
- 26. • Acuminate -Gradually narrowing at the base. • Acute -Becoming Gradually Pointed • Rounded -A curved base with margins that form a smooth arc.
- 27. • 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.
- 28. • Hastate -a base with pointed lobes directed outwards. • Truncate -a broad straight base, abruptly ending at right angles to the midvein