Morphology of Flowering Plants

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Å TÝPÏÇÅL LËÅF HÅS 3 MÅÏÑ PÅRTS:

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Leaf base: With this, the leaf is attached to stem. It may bear two lateral

leaf-like structures called stipules. In monocots, the leaf base expands

into a sheath covering the stem partially or wholly. In some leguminous

plants, the leaf base may be swollen. It is called pulvinus

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Petiole: It helps to hold the leaf blade to light. Long thin flexible petioles

allow leaf blades to flutter in wind, thereby cooling leaf and bringing

fresh air to leaf surface.

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Lamina (leaf blade): The green expanded part with veins & veinlets. The

middle prominent vein is called midrib. Veins provide rigidity to lamina

and act as channels of transport for water, minerals & food materials

1. VËÑÅTÏØÑ

It is the arrangement of veins and veinlets in leaf lamina.

Reticulate venation

Parallel venation

2 Types

Here, the veinlets form

a network. It is seen in

dicotyledons.

Here, the veins run parallel to

each other within a lamina. It

is seen in monocotyledons.

2. TÝPËS ØF LËÅVËS

Simple leaf: Here, leaf lamina is entire or when incised, the incisions do not touch the

midrib.

Compound leaf: Here, the incisions of the lamina reach up to the midrib breaking it

into several leaflets.