How are leaves made up and what is the structure of leaves?

General structure of angiosperm leaves.

Heterofacial leaves – The internal structure of the two sides is different, dark green on the top and light green on the bottom.

Isofacial leaves – the internal structure of both sides is similar, and the mesophyll tissue is not very differentiated.

Three basic structures:

1 Epidermis – enveloped in the outermost layer of the leaf and has a protective effect.

A The presence of stratum corneum plays a protective role, controls water transpiration, strengthens mechanical properties, prevents the invasion of germs, and has different degrees of absorption capacity for liquid medicine.

b The thick wall of the cuticle can be used as one of the bases for the breeding of excellent crop varieties.

c Stomata are composed of guard cells and the orifices between them.

d Types of pores: irregular, unequal, flat, horizontal.

2 Mesophyll - in the inner part of the epidermis, it has the function of producing and storing nutrients.

Palisade tissue: The green tissue near the upper epidermis is neatly arranged, and the cells are long cylindrical, and the long axis of the cells is perpendicular to the leaf surface, which is palisade-shaped.

Sponge tissue: the green tissue below the palisade tissue, that is, near the lower epidermis, irregularly shaped, unneatly arranged, loose and with many gaps, making it spongy

3 Leaf veins – vascular tissues buried in the mesophyll that have a transductive and supportive role.

Summary: Mesophyll is the main structure of the leaf, and it is the main place where the physiological function of the leaf is carried out. The epidermis is covered and protects, allowing the mesophyll to work smoothly.

On the one hand, the water and salts required by the mesophyll tissue are endlessly transported, and the products of photosynthesis are transported at the same time; On the other hand, it supports the leaf surface, so that the leaf stretches in the atmosphere and withstands light. The rational combination and organic connection of the three basic structures also ensure the smooth progress of the physiological function of the leaf, which also shows that the shape and structure of the leaf are fully adapted to its physiological function.

Leaves are generally composed of three parts: the leaf, the petiole and the supporting leaf.

1. Leaves: Leaves are composed of three parts: epidermis, mesophyll and veins. Leaves are important organs for plants to produce nutrients, and are important places for photosynthesis and respiration.

2. Petiole: The petiole is the part that connects the leaf and the stem, and its main function is to transport and support.

3. Supporting leaves: Its functions are different, for example, the supporting leaves of peas can carry out photosynthesis, while the supporting leaves of sour jujube can become thorns.

What it does:

1. a blade. The leaf is composed of three parts: epidermis, mesophyll and vein. The essence of photosynthesis is the process of green plants using light energy through chloroplasts, synthesizing carbon dioxide and water into organic matter, and releasing oxygen. Respiration is the process by which plants absorb oxygen, break down organic matter into carbon dioxide and water, and release the energy needed for plant growth.

2. a petiole. The petiole is the part that connects the leaf and the stem, the upper end is connected to the leaf, and the lower end is connected to the stem. The main function of the petiole is to transport and support, there are vascular bundles inside the petiole, which is the main channel for water and nutrient transport between the stem and leaf, and the moon cake is generally cylindrical or slightly flattened.

3. Supporting leaves. The leaves are born at the junction of the petiole and the stem, respectively, on both sides, and its form and function have certain differences according to different plants, for example, the leaves of peas can carry out photosynthesis, while the leaves of jujube can become thorns, and the leaves of more plants will fall off in the process of growth.

Leaves are generally composed of three parts: epidermis, mesophyll, and veins.

1. The epidermis is a layer of primary protective tissue on the surface of the leaf, which covers the entire leaf, and is mostly composed of a layer of closely arranged flat epidermal cells, but there are a few exceptions to the plantation curve, such as the epidermis of oleander leaves and tung leaves, which are excavated and rented by 2 or 3 layers of cell groups. There is often a stratum corneum or waxy layer on the upper epidermis, and some epidermal cells often differentiate to form stomata or various appendages.

2. The mesophyll is an assimilated parenchyma tissue, located between the upper and lower epidermis, including palisade tissue and sponge tissue. The palisade tissue is cylindrical, the cells are closely arranged, perpendicular to the epidermis, containing chloroplasts, which can perform photosynthesis and make nutrients. The spongy tissue is irregular, loosely arranged and spongy, which is conducive to gas exchange, contains a small amount of chloroplasts, and is located in the judgment grid.