Leaves are a plant’s powerhouse, using sunlight to join water and carbon dioxide to make sugar, the plant’s fuel.
Leaves are broad and flat to catch maximum sunlight.
Leaves are joined to the stem by a stalk called a petiole.
The flat part of the leaf is called the blade.
The leaf blade is like a sandwich with two layers of cells holding a thick filling of green cells.
If you hold a leaf blade up to the light, you can clearly see the pattern of its veins.
The green comes from the chemical chlorophyll. It is this that catches sunlight to make sugar in photosynthesis.
Chlorophyll is held in tiny bags in each cell called chloroplasts.
A network of branching veins (tubes) supplies the leaf with water. It also transports the sugar made there to the rest of the plant.
Air containing carbon dioxide is drawn into the leaf through pores on the underside called stomata. Stomata also let out water in a process called transpiration.
To cut down water loss in dry places, leaves may be rolled-up, long and needle-like, or covered in hairs or wax. Climbing plants, such as peas, have leaf tips that coil into stalks called tendrils to help the plant cling.