What the leaves of a plant are made of, and what they are made of

The leaves of the plant are made up of epidermis and mesophyll.

A cross-sectioned section from the blade allows the following structure to be observed from the outside in.

1. Epidermis: It is a layer of primary protective tissue on the surface of the leaf, usually divided into upper and lower epidermis, the upper epidermis is located on the ventral surface, and the lower epidermis is located on the back. Epidermal cells are flat, tightly packed, and usually do not contain chloroplasts, often with a stratum corneum on the outside.

Some epidermal cells often differentiate to form stomata or protrude outward to form hairs.

2 Mesophyll: It is an assimilated parenchyma tissue in the epidermis, usually of the following two types.

1) Palisade tissue: Immediately below the upper epidermis, the cells are usually 1 to several layers, long cylindrical, perpendicular to the epidermal cells, and closely arranged in a grating shape, containing more chloroplasts. In bihedral or needle-shaped leaves, palisade tissue is also distributed above the lower epidermis or around the entire inner epidermis, but there are also some aquatic and shade plants whose leaves are completely defence-free.

2) Sponge tissue: the shape of the cells is more irregular, containing less chloroplasts, located below the fence tissue, the layers are unclear, loosely arranged, and the shape is like a sponge.

3) Leaf veins: vascular bundles that run through the mesophyll. The vascular bundles of the main vein are thicker, and the vascular bundles of the lateral veins and small veins are smaller, usually with limited external toughness above the xylem, and less bitough type with xylem in the middle.

The vascular bundles are surrounded by predominantly parenchyma tissues, and asymptotic approaches to the epidermis often have thick-angled or thick-walled tissues, which are usually more protruding and particularly well-developed below the main veins. Calcium oxalate crystals are very common in leaf tissues and come in a variety of shapes, depending on the plant species.

The leaves of a plant are made up of epidermis, mesophyll, and veins.

The leaves of plants are generally made up of (Blades, petioles, leafletsComposed of three parts.

These three parts are possessed and are called complete leaves. Whereas, a leaf that lacks any or both of these parts is called an incomplete leaf.

Leaves are the most important components of leaves, mostly thin green flat bodies, this thin and flat form, with a large surface area, can shorten the distance between mesophyll cells and the leaf surface, and the leaf veins that play a supporting and conductive role are also in a network state. These characteristics are conducive to gas exchange and light energy absorption, the transport of water and nutrients and the output of photosynthetic products, and are perfect adaptation to photosynthesis and transpiration.

The petiole is the stalk-like part that follows the base of the leaf, and its lower end is connected to the branch. The main function of the petiole is to guide and support, the petiole can twist and grow, thereby changing the position and direction of the leaf, so that the leaves do not overlap each other, and can fully receive sunlight, this characteristic is called leaf mosaic.

The leaves are appendages at the base of the petiole and are often born in pairs. Its shape and function vary depending on the plant species, in addition to the protective effect on young leaves, some green leaves can also carry out photosynthesis.

The leaves of grasses are different from the leaves of general plants, and it is composed of two parts: leaves and leaf sheaths. The leaves are linear or band-shaped, with longitudinal parallel veins. The leaf sheath is long and narrow and holds the stem, which has the role of protection, support and conduction.

Composition of leaves.

Although the morphology of the leaves is diverse, the basic composition is the same. It is composed of three parts: petioles, veins, and leaves. The leaves that all three parts have are called complete leaves, such as the leaves of peach trees, willows, moons, and other plants.

Some plants have leaves that have only one or two of them, which are called incomplete leaves. For example, cabbage leaves, which do not have supporting leaves.

The main component of the leaf is generally a thin green flat body, with an upper surface and an lower surface. The whole shape of the leaf is called the leaf shape, the tip is called the leaf end or the tip of the leaf, the base is called the leaf base, the periphery is called the leaf margin, and there are leaf veins distributed in the leaf.

The petiole is the part of the leaf and stem that connects to each other, and is generally cylindrical, semi-cylindrical, or slightly flattened. The pediment is an appendage of the base of the petiole and is often born in pairs on either side of the base of the petiole. It also comes in a variety of shapes.

Like pears and mulberry trees, the leaves are relatively small and linear. The leaves of peas are large and leaf-like.