Revision Lesson for WASSCE candidates-Biology: The Leaf of a plant

A leaf is actually called ‘the kitchen of the plant’.  This is because they are the main organ responsible for photosynthesis, through which the plant produces its energy (also known as it’s food). They obtain their green color due to the presence of chlorophyll.


A leaf is the green, flat lateral outgrowth in plants. They come in different shapes and sizes, and colors, and are generally dorso-ventrally flattened and thin. They are the main organ responsible for photosynthesis as they contain chlorophyll.

Parts of a Leaf

Leaves have two main parts: The leaf blade and the Stalk or the petiole.

  • The leaf blade: It is also called the lamina. It’s generally broad and flat. It is in this layer that photosynthesis occurs. It contains a prominent midrib at the center of the leaf blade which is the main vein. From this midrib arise branches called veins. They are of different types depending upon the type of edges, the pattern of the veins and the number of blades per leaf.
  • The petiole: It is the stalk-like structure which connects the leaf blade to the stem. The petiole has tiny tubes, that connect the veins on the leaf blade to the stem. Few of these enable water transport to the leaf while the other carry food away from the leaf to other parts of the plant.

Some plants also contain another part called stipules. These are small flap-like structures that grow at the base of the petioles. They are protective in some plants when they protect the growing petiole while in others, they fall off once the petiole starts growing.

One thought on “Revision Lesson for WASSCE candidates-Biology: The Leaf of a plant

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