The **leaves** of the plant are the main structures or organs for photosynthesis. In order to efficiently collect sunlight, the leaves are characterized by having thin, flat sections called *blades*, and these are then attached to the *petiole* which is the thin structure that attaches it to the stem.

When the balance of water is high in the plant, the guard cells are swollen with water, creating an opening, where water is lost through. However, when the balance of water is low in the plants, the guard cells shrivel and close, preventing water from escaping.

**Stomata** are the tiny openings present on the epidermis of leaves that regulates the exchange of gases. Because hot temperatures increase transpiration, the plants will lose water at a faster rate, forcing the ***stomata to be closed most of the day***.

The specialized cells found in a leaf are the following:

Palisade mesophyll – a layer of mesophyll cells found under the epidermis; responsible for absorbing the light that enters the leaf

Spongy mesophyll – located beneath the palisade layer; it contains air spaces that are connected to the stomata

Stomata – pores of the leaf; it allows gas exchange in and out of a leaf

Guard cells – found in the stomata; by responding to the water pressure changes in the leaf, it can control the opening and closing of the stomata

Since leaves are responsible for the process of photosynthesis, they have a way to obtain the materials needed and distribute the end products of photosynthesis. The structure of a leaf is specifically designed to fulfill this function. Because the vascular system of a stem is connected to the vascular system of the leaves, the leaves are considered an important part of the transport system too. Just like in the stem and root systems, the leaves have xylem and phloem, which aids in the transport of water and minerals; and dermal tissues, which serve as an outer protective layer of the vascular tissues and ground tissues.

**Leaves** are the flattened structure of a plant, usually green in color and blade-like in shape. Some are directly attached into the stem of a plant and others via connecting stalk (petiole). Leaves are the main organ for photosynthesis.

Photosynthesis occurs in the specialized tissue of the leaves called the **mesophyll**. The *palisade mesophyll* specifically functions in light absorption and helps in minimizing transpiration. Hence, since there is little or no water available in the desert. The two layers of palisade mesophyll will be an advantage to them as it helps and allows the plant to survive by preventing an increase in transpiration due to high weather temperatures.