The leaf is a lateral generally flattened structure borne on the stem. The leaves develop from the nodes. Their main function is photosynthesis and food making, axillary buds are found in its axil. All the leaves of a plant is known as phyllome. Axillary bud later develops into a branch. Leaves originated from shoot apical meristem and are arranged in acropetal order

Leaf is divided into 3 main parts :

Leaf base

✧ Leaves are attached to stem by leaf base.

Petiole

✧ The part of leaf connecting the lamina with the branch of stem. Petiole help to hold the blade to light.

Lamina

It is a broad and flattened part of leaf. Its main functions are photosynthesis and transpiration. Shape of lamina are :

• • • • Acicular – Lamina is long and pointed, like a needle. eg. Pinus

      • Lanceolate – In this type lamina is pointed or narrower at the ends while broader in the middle. eg. Bamboo, Nerium

      • Linear – The lamina is long and narrow having parallel margins. eg. Grass

      • Ovate – In this type lamina is egg-shaped having broad base with slight narrow top. eg. Ocimum, Banyan, China rose.

      • Cordate – Its shape is like a heart. eg. Betel

      • Oblong – Long and broad lamina. eg. Banana

      • Sagittate – The lamina is triangular in shape. eg. Sagittaria

      • Spathulate – The lamina is broad spoon shaped. eg. Calendula

      • Orbicular or Rotund – In this types the lamina is spherical. eg. Lotus.

      • Elliptical or Oval – In this type the middle part of lamina is broad while the ends are narrow and oval. eg. Guava.

      • Oblique – In this types midrib divides, lamina into two unequal halves. eg. Bignonia, Neem.

Stipules :

Leaves of some plants have lateral appendages on either side of leaf base, known as stipules. If stipules are present in leaf it is called stipulated leaf, if it is absent then leaf is called ex stipulated

VENATION OF LAMINA

The arrangement of veins and veinlets in leaves (Lamina) is known as venation. It is of 2 types

• • • • • • • Reticulate : It is found in dicots. Exception – Calophyllum, Eryngium. It has parallel venation.

            • Parallel : It is found in monocots. Exception – Smilax, Dioscorea, Alocasia, Colocasia. It has reticulate veination