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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