Leaves
Leaves vary in appearance, but they have a similar anatomy and function in the same way. All green leaves are involved in photosynthesis, gas exchange and transpiration.
Chloroplast
Photosynthesis takes
place in it: the production of sugar from carbon dioxide, with the help
of solar energy.
Stoma
Gas exchange and transpiration takes place through the stoma.
The plant can close its stomata in order to prevent drying out.
Cuticle
A waxy protective layer that covers the surface of leaves.
Epidermis
It consists of one layer of cells. Its cells do not contain chloroplasts, with the exception of the guard cells of the stomata. It serves to protect the plant, and to maintain contact with the environment.
Xylem
The xylem transports water and mineral salts.
Phloem
Sugars produced during photosynthesis are transported to the rest of the plant by the phloem.
Assimilation tissue (mesophyll)
This is the primary location of photosynthesis. Due to the high
number of chloroplasts; the mesophyll tissue is green.
Secondary vein (lateral vein)
Petiole
Primary vein (midrib)
Why are leaves colourful in autumn?
As trees prepare for winter, they shed their leaves. However, before that, leaves turn yellow, brown or red. This begins when days become shorter and nights get colder. At this time, plants produce less and less chlorophyll and, as a result, we can see the colours of other pigments in the leaves, for example, carotenoids, which are yellow or orange; or anthocyanins, which are red or purple.
The anatomy of the leaf blade
The inner and outer layer of cells that cover leaves is called the epidermis. The bulk of leaves is composed of mesophyll tissue. Its top layer consists of vertically elongated cells, while the bottom layer has a spongy texture.
A vein is made up of a vascular bundle. The xylem typically lies on adaxial side of the leaf.
The Anatomy and Development of Plants
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The Anatomy and Development of Plants
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