Function of Leaves

In botany, a leaf is any green protrusion from the stem of a vascular plant that is typically flattened. Leaves, as the principal sites of photosynthesis, produce food for plants, which in turn provide nourishment and sustenance for all terrestrial creatures. In botany, leaves are considered to be an important element of the stem system. They are connected to the rest of the plant by a continuous circulatory system, which allows for the free exchange of nutrients, water, and end products of photosynthesis (oxygen and carbohydrates, in particular) to be transported to the various regions of the plant’s body. Leaves, as well as the tissues of the stem itself, are initiated in the apical bud (growing tip of a stem). Certain organs that appear to be very different from the typical green leaf are modified leaves that are formed in the same way as the usual green leaf; for example, the sharp spines of cacti, the needles of pines and other conifers, the scales of an asparagus stalk, and the bulb of a lily are all modified leaves.

Various types of leaves

1. Plain and Simple Leaves

Each leaf has only one undivided leaflet and is linked to the stem using a single leaflet. It is always attached to a twig by its stem or petiole, which is a little leaf.

Maple, oaks, banana, guava, mango, black cherry, black gum, and sweet gum are just a few examples.

2. Leaves with a compound structure

A leaf that is formed of numerous leaflets that are linked to the midvein and each has its stalk is known as a compound leaf. Neem, rose, clover, desert cotton, poison ivy, horse chestnut, and baobab are examples of plants.

Based on the types of leaf veins present and how they are arranged inside the lamina, complex leaves are further subdivided into two categories:

1. a) Leaf with a palmately complex structure

Their shape is similar to the fingers on the palm of our hands, as they are leaflets that radiate forth from the end of the petiole.

The palmately complex leaf can be classified into the following types based on the number of leaflets on the leaf: a. Unifoliate plants have one leaflet, bifoliate plants have two leaflets, and trifoliate plants have three leaflets, quadrifoliate plants have four leaflets, and multifoliate plants have five or more leaflets.

Citrus limon (unifoliate), Bauhinia yunnanensis (bifoliate), Acer cissifolium (trifoliate), Oxalis (quadrifoliate), and Umbrella plant are examples of unifoliate plants (multifoliate).

1. b) A leaf with a pinnately complex structure

They are leaflets that are aligned symmetrically down the centre of the leaf, with each leaflet appearing to be connected or pinned to the midrib, giving the leaf the appearance of a feather when viewed from the top or bottom.

Plants with pinnately compound leaves are classified into the following groups according to how many times the leaflet is linked to the midrib: A unipinnate leaf has a single compound leaf oppositely attached to the midrib, a bipinnate leaf has multiple compound leaflets oppositely attached to the midrib, and a tripinnate leaf has multiple compound leaves attached to the midrib oppositely.

Function of leaves

Photosynthesis is the primary function of a leaf, and it is responsible for producing food for the plant. Chlorophyll, the pigment that gives plants their distinctive green colour, is responsible for the absorption of light energy. To safeguard its internal structure, the leaf epidermis is continuous with the stem epidermis, which means that it is a single layer. The centre leaf, or mesophyll, is made up of cells with soft walls and no specialization, which is classified as parenchymal cells. Even more, than a fifth of the mesophyll is made up of chloroplasts, which contain chlorophyll and absorb sunlight, allowing them to utilize the radiant energy to decompose water into its constituent elements of hydrogen and oxygen in combination with specific enzymes. Because of plant and animal respiration, as well as combustion, oxygen is released from green leaves, which helps to replenish the oxygen taken from the atmosphere by these processes. As a result of photosynthesis, the hydrogen acquired from water is mixed with carbon dioxide in the enzymatic processes of photosynthesis to generate the sugars that serve as the foundation for both plant and animal life. Stomata, or pores on the leaf surface, are responsible for the exchange of oxygen with the surrounding environment.

Conclusion

A leaf is typically composed of a broad extended blade (the lamina), which is linked to the plant stem by a stalk similar to the petiole. The stipules of angiosperm leaves are a pair of structures found on either side of the leaf base that can take the form of scales, spines, glands, or leaf-like structures. Stipules are found in angiosperm leaves and are found on both sides of the leaf base. Leaves, on the other hand, are extremely variable in terms of size, form, and a variety of other properties, such as the nature of the blade margin and the type of venation (arrangement of veins). Simple leaves are those in which only a single blade is put directly onto the petiole, as opposed to compound leaves. Simple leaves might have their margins completely smooth or they can have them lobed in a variety of ways. Dentate margins have coarse teeth that protrude at right angles to the leaf apex, whereas serrate margins have fine teeth that point toward the leaf apex. Crenulate margins are characterized by rounded teeth or scalloped edges. Simple leaves have leaf margins that are lobed in either a pinnate or a palmate pattern, depending on their shape. As in the white oak (Quercus alba), the leaf blade (lamina) is indented equally deep along each side of the midrib, whereas in palmately lobed margins, the leaf blade (lamina) is indented along several major veins. Pinnately lobed margins are found on leaves with a midrib that is indented equally deep along each side of the midrib (as in the red maple, Acer rubrum).