Nutrition and respiration - these are the vital functions that plant leaves can carry out. Vines and cacti, cereals and water lilies - each of these plants gives a unique look to the leaves.
Leaf - lateral part of the shoot
The shoot of any plant consists of the axial part - the stem, to which the leaf is attached - the side part. This arrangement allows the sheet to occupy the most favorable position in relation to the sun. The shape and size of the leaves depend on the habitat of the plant. For example, plants in moist areas have leaves with large leaf blades for a more intensive process of water evaporation. If the plant grows in an area with a dry climate, there is no need to lose moisture. Therefore, the leaves of such plants will be small and thin. So wisely, nature created a leaf whose functions are so important for plant and animal organisms.
In addition, some leaves may change their shape with changing environmental conditions. The well-known arrowhead in water has a ribbon-like leaf shape. It is necessary so that this organ cannot damage the strong flow of water. When water becomes less and some leaves die off, arrow-shaped leaves grow in their place. Their photosynthetic surface is much larger, which means that the chances of the plant to survive significantly increase.
External structure
The leaf consists of a leaf blade and petiole, with the help of which it is attached to the stem. Some leaves lack a petiole, and the base of the leaf blade serves as the place of their attachment. Such leaves are called sessile.
Each leaf blade has its own method of dismemberment. So, willow leaves are whole-edge, oak leaves are ciriform-lobed, and for dandelion - cirrus-separated. Everyone knows the palmate leaves of a chestnut tree and the triple leaves of clover.
Internal structure
The functions of the plant leaf are interconnected with the features of its internal structure. Outside is a living integumentary tissue - the skin. She not only protects the sheet. The functions of metabolism, water evaporation and gas exchange are performed by stomata - special skin structures. They have flaps that can open and close depending on the need for the intensity of the process.
The main part of the leaf is filled with chlorophyll-bearing and storage tissue. It creates mass, stores water with a solution of nutrients and implements a complex process of photosynthesis.
The absorption and movement of substances - these functions of the plant leaf provide conductive tissue. They are represented by xylem, in the vessels and tracheids of which an upward current occurs. Another of its varieties is the phloem, which is responsible for the opposite flow of substances - the descending one. After all, sugars formed in leaves due to solar energy are necessary for all plant organs, including the root.
Since such a complex organ, as a sheet, the functions of conducting substances carry out the opposite, the elements of its conducting system are bundled.
These structures are covered with elements of mechanical tissues and together form vascular-fibrous bundles. Simply called veins.
Thanks to this structure, the conducting bundles in the leaves perform the functions of the movement of substances, as well as the supporting and mechanical ones.
Venation
Such conductive beams are visible to the naked eye. On a sheet plate, they form a special unique pattern like human fingerprints. Here is another function of bundles in leaves.
There are several types of venation. Mesh can be easily determined by the presence of the main vein, from which smaller ones depart, forming a mesh. Surely everyone saw such an image on the leaves of plums, apricots or cherries.
Lily and wheat have thin leaves, veins on which are located next to each other. This type is called parallel. But the veins of lily of the valley leaves are similar to arcs - this is the arc venation.
Regardless of the type of arrangement, the conducting bundles in the leaves perform functions without which plant life would simply be impossible.
Types of leaves
Leaves are also classified by the number of leaf blades. Simple are called single-leaf leaves. Peach, cherry plum, maple, medunica are examples of plants with simple leaves. Complex leaves have acacia, walnut, alfalfa. They consist of several leaf blades attached to one petiole.
What is the function of the sheet
With the help of leaves, vegetative propagation is possible. Its essence is to separate its multicellular part from the whole organism. At home, so you can propagate violet or zigocactus.
Important for plants and transpiration - the process of evaporation of water. If it does not occur, the plant organism will die. Since the temperature of the internal environment of all representatives of the plant kingdom depends on the ambient temperature, they can simply overheat.
The leaves of some plants are able to mutate. So, the tendrils of peas provide its firm attachment to the support, the cactus spines protect from excessive moisture loss, the fleshy aloe leaves provide a supply of water with nutrients.
Green leaf: functions of planetary significance
The following leaf functions are two reverse processes - photosynthesis and respiration.
Breathing is the process of absorbing oxygen and releasing carbon dioxide. It is a necessary condition for the existence of all living organisms and is characteristic of representatives of almost all kingdoms of wildlife.
Photosynthesis is the process of formation of organic substances from inorganic substances due to the energy of light. This process can occur only in the leaves, since they contain the green pigment chlorophyll. Its implementation requires carbon dioxide, which is released in sufficient quantities during breathing. And as a result of photosynthesis, glucose and oxygen are formed.
Without exaggeration, we can agree that the green leaf is a real factory that produces not just chemicals, but also provides all life on our planet with the necessary conditions for life.