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Prepared by:Group 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.
• 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.
Parts of the leavesLeaf Internal Anatomy
Parts of the leavesoLower epidermis – outmost tissue on the
lower side of the leaf; protects the leafoUpper epidermis – outmost tissue on the
upper side of the leaf; protects the leafoMesophyll – all of the middle tissue of the
leaf Palisade layer Spongy layer
Parts of the leaveso 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
• 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.
Leaf External AnatomyParts of the leaves
Parts of the leaves• 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
oMidrib – main vein; continuation of petioleo Leaf tip- leaf apex of the outer end of the leafo Leaf Base – expanded area where leaf attached
Simple Leaf
• Simple leaf = undivided blade with a single axillary bud at the base of its petiole.
Compound leaf
• 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
Leaf Arrangements (Compound)
• 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
Leaf Arrangements (Simple)
• 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.
Leaf Venation
Leaf Shape
acicular
hastate
falcate
obovate
Leaf Margin• 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
Leaf Margin• 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.
Leaf Margin• 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.
Leaf Margin• 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.
Leaf Margin• Denticulate– With fine dentition
• Ciliate– With fine hairs
Leaf Tip• Acute -Ending in a sharp,
but not prolonged point
• Acuminate -Long-pointed,
prolonged into a narrow, tapering point in a concave manner
Leaf Tip• Cuspidate -With a sharp,
elongated, rigid tip; tipped with a cusp
• Emarginate -Indented,with a
shallow notch at the tip
Leaf Tip• Aristate -having an awn.
• Mucronate -ending in a
mucro or sharp point.
Leaf Tip• Obtuse -not sharp or
pointed; blunt.
• Truncate - having a square
or broad end.
Leaf Base• Acuminate -Gradually narrowing
at the base.• Acute -Becoming Gradually
Pointed• Rounded -A curved base with
margins that form a smooth arc.
Leaf Base• 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.
Leaf Base• Hastate -a base with pointed
lobes directed outwards.
• Truncate -a broad straight
base, abruptly ending at right angles to the midvein
Internal & External View
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