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Inside A Leaf- A leaf contains long strips of vascular tissue* called veins. These supply the leaf with water and minerals, and move the food made inside the leaf to other parts of the plant.

Some leaves, such as grasses, have long, parallel veins, but most contain one central vein called midrib. This is an extension of the leaf stalk. Themidrib branches into a number of smaller veins, called side veins. A leaf’s whole vein system is called its venation.

Leaf Cells- A leaf is made up of layers of different types of cells. The epidermis is a layer of flat, waxy cells on the surface of the leaf. It prevents too much water from being gained or lost.

The palisade layer lies just beneath the epidermis, on the leaf’s upper side. It is made up of column-shaped palisade cells, which contain many tiny green chloroplasts*. The contents of palisade cells are packed closely together, which helps them to absorb sunlight.

Under the palisade layer is the spongy layer, made up of irregularly shaped spongy cells and air spaces. The spaces allow air to move around inside the leaf. The spongy layer and palisade layer together are called the mesophyll.

Surface Of A Leaf- On the underside of a leaf are tiny holes called stomata, each one called a stoma. These allow water and air to move in and out of the leaf.

On either side of each stoma  is a crescent-shaped guard cell. These paired cells can change their shape to open and close the stoma, controlling hoe much air and water enters and leaves the leaf.

Leaf Stalks- A leaf stalk or petiole is a thin structure which joins the main body of a leaf to the stem. It contains the leaf trace. This is an area of vascular tissue which branches off the vasular tissue of a stem and becomes the leaf’s central vein. This vein allows minerals to be carried into the leaf.

Before a leaf dies, a layer of cells called an abscission layer forms at the base of its stalk. The abscission layer seperates the leaf from the rest of the plant. The leaf then falls off, creating a leaf scar on the stem.

Color In Leaves- Leaves get their color from chemicals called pigments. Most leaves are green because they contain a green pigment called chlorophyll. variegated leaves are patterned because they only have pigments in certain places on their surface.

Other pigments include xanthophylls, which produce yellow shades, and carotene, which makes leaves look red or orange. These pigments are present in many plants, but are usually masked by chlorophyll. After summer has ended, the chlorophyll. in most plants breaks down, revealing the other pigments.