Why are the front and back colors of the leaves of plants different?

The color of flower leaves is mainly determined by the plant pigments such as chlorophyll, lutein, carotenoids, and anthocyanins contained in the leaf cells. Chlorophyll a is blue-green and chlorophyll b is yellow-green, and because they are found in different chloroplasts in different flowers, some leaves are dark green, while others are pale green or grass green.

Carotenoids are the color source that makes leaves orange, anthocyanins are the color source that makes leaves red and blue, and lutein is the color source that makes leaves yellow. The epidermal cells of most flowers contain only chlorophyll, so the leaves are mostly green. Green is the basic color of plant leaves, but if you look closely, there are differences such as tender green, light green, bright green, dark green, yellow-green, reddish green, brownish green, blue-green, dark green, and dark green.

The epidermal cells of some flower leaves contain a large amount of carotenoids, anthocyanins and lutein and other pigments, or they are very abundant in a certain part of the leaves, so they form colored leaves.

For example, leafy flowers such as dogwood and beet contain anthocyanins in their mesophyll cells, so the whole leaf is red;

The leaves of Phyllostachys nantianensis and red mulberry are more chlorophyll synthesized under low light, and carotenoids and anthocyanins are synthesized more under strong light or low temperature, so the leaf color is green when cultivated in semi-shade, and the leaves are purple-red or orange-red when placed in strong light maintenance or spring and autumn;

Different parts of the leaves of Phnom Penh spider plant and Phnom Penh agave contain chlorophyll and lutein respectively, so the leaves show two colors of yellow and green.

In addition, the same is true for foliage plants such as Variegolia with a variety of leaves, which have a variety of colors.

In the same way, the discoloration of the fruit is also the result of the change of pigment. The green color of the peel is mainly caused by chlorophyll, and as the fruit matures, the chlorophyll content decreases and the carotenoids and anthocyanins increase, resulting in a yellow, orange-red or red color.

The epidermis of the leaf is made up of a tightly arranged, colorless, transparent layer of cells. The outer wall of epidermal cells has a stratum corneum or wax layer that plays a protective role. There are many pairs of half-moon-shaped guard cells on the epidermis.

The green parenchyma located between the upper and lower epidermis is collectively called mesophyll, which is the main site of photosynthesis in leaves, and its cells contain a large number of chloroplasts. The leaves of most plants are located in a transverse position on the branches, and the leaves are divided into upper and lower leaves. The upper side (paraxial, ventral) is the light-receiving side, which is dark green.

The lower side (distal axial face, back) is the backlit side, which is pale green.

Due to the different light reception conditions on both sides of the leaf, the mesophyll tissue inside the two sides is often organically differentiated, and this kind of leaf is called heterofacial leaf. The leaves of many monocots and some dicots are born in an almost upright position, and the two sides of the leaves receive light evenly, so the internal mesophyll tissue is relatively uniform, and there is no obvious tissue differentiation, such leaves are called equifaced leaves, such as corn, wheat, and Populus euphratica. In heterofacial leaves, the mesophyll tissue cells near the upper epidermis are long cylindrical, closely arranged, and their long axis is often perpendicular to the leaf surface, in the form of a palisade, so it is called palisade tissue, and the number of layers of palisade tissue cells varies according to the plant species, usually 1 3 layers.

The mesophyll cells close to the lower epidermis contain fewer chloroplasts, the shape is not planned, the arrangement is loose, and the intercellular space is large and numerous, and it is spongy, so it is called spongy tissue.

Because leaves contain not only chlorophyll, but also carotene and lutein, and the color will be different if the content is different. The color of the flowers is mainly due to flavonoids.

This is mainly the result of plant evolution, i.e. natural selection and adaptive evolution. Due to the different conditions of care, temperature, humidity and other conditions, plants have produced different leaves through long-term natural selection in order to survive better.

Leaves are the main organs of plant assimilation and transpiration, and they are considered to be the most sensitive to environmental changes in the process of plant evolution.

Organs with strong plasticity have formed different types of adaptation to adversity under various selection pressures, and their morphological and anatomical characteristics are the most numerous.

It can reflect the adaptation of plants to the environment.

Leaf anatomy has been shown to be closely related to the exchange of matter and energy between the inside and outside of the leaf and its own protection.

Linkage is the skeleton that constitutes the morphological structure of leaves, and it is also an important content to study the morphological structure characteristics of leaves and the ecological adaptation strategies of plants.

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In the summer, it is very hot outside, but the forest is shady, and this is all due to the trees. Tiny leaves on the trees shade us from the sun. Bright light.

But you have noticed that the color of the front and back is different without leaves, but why is that? I believe that many friends don't know much, so I'll answer your doubts by 5068.

It turns out that the leaves of plants are green because they contain chlorophyll. Since chlorophyll is green, when the mesophyll cells contain a large amount of chlorophyll, the leaves will appear green, and the more chlorophyll content, the darker the green color. By observing the internal structure of the leaf, scientists found that the cells on the front of the leaf are very tightly arranged and very neat, looking like rows of fences, called fence organization; On the back of the leaves, the cells are very loosely arranged, the voids are large, and there are no irregularities, like a sponge, which is called sponge tissue.

The reason why the cells of the fence tissue contain more chlorophyll is for photosynthesis, under normal circumstances, the front of the leaf can receive sunlight, and only if it contains more chlorophyll, can it produce more nutrients; On the backlit side, because there is little photosynthesis, it does not need much chlorophyll, so the chlorophyll content is less.