The leaves are vegetative organs which generally flattened. It is located laterally on the stem, in charge of photosynthesis.
The morphology and anatomy of stems and leaves are closely related. One organ cannot exist without the other; together, they constitute the stem. There are The leaves animated pictures below. Lets check this out.
Leaves Animated Pictures
The leaf is one of the essential parts of the vascular plants. It is the vegetative organ primarily specialized in carrying out photosynthesis. It is also part of the plant that carries out photosynthesis, as well as breathing and plant transpiration.
In general, leaves are lamellar or acicular structures, which sprout laterally from the stems or branches. It has limited growth and contains mostly photosynthesizing tissue, always within reach of light.
Also, the leaves are responsible for carrying out other functions such as transpiration and respiration. Secondarily, the leaves can be modified to store water or for other purposes.
The leaf fulfills several functions in the plant, such as photosynthesis, breathing, or transpiration. These functions can also be carried out by the herbaceous stems and by the young portions of the woody stems. In some plants that lack leaves, such as cacti, these functions are performed by the stems.
Photosynthesis, also known as chlorophyll function, consists of the synthesis or production of organic substances with nutritional properties (sugars) from atmospheric CO2, which the leaves absorb through the stomata, and from the water provided by the plant’s roots. This process requires an energy consumption that is obtained from sunlight, and in it, oxygen is generated.
Photosynthesis is an essential process for life on the planet, since it allows the production of organic matter from inorganic matter and the energy provided by sunlight, and generates the oxygen that is emitted into the atmosphere.
Photosynthesis is made possible by unique pigments contained in plants, the most important of which is chlorophyll, which is responsible for the green color of plants.
Breathing is the process by which the energy necessary to develop the biological activity. It is obtained through the metabolization of the products (sugars) purchased through photosynthesis.
Breathing requires the intake of oxygen from the atmosphere and the emission of CO2. During the day, respiration is masked by photosynthesis but, during the night, the plant only breathes, releasing carbon dioxide and absorbing oxygen.
Respiration is carried out by all the living cells of the plant, not just those of the leaves. The gaseous exchange takes place mostly through the stomata, which are much more abundant in the leaves than in other parts of the plant.
Transpiration consists of the loss of water that, in the vascular plants, is carried out through the stomas. It is a fundamental process for the raw sap moving from the soil to the leaf and controlling the temperature of the plant.
Fallen leaves are the process of defoliation that occurs naturally in plants. This process of defoliation is called chorism.
If the stimulus that provokes it is internal, we have autochorism, the most frequent of all and a periodic nature; thermochromism, chemochorism, or traumatochorism, when the thermal, chemical or traumatic factors are those that determine the fall of the leaves.
When the leaves fall, the transpiring surface is significantly reduced, so that the plant can resist cold periods or those of exceptional drought in a state of stifled life.
Leaf fall in deciduous plants is due to an interesting phenomenon of cell reabsorption. The detachment of the leaf always occurs in a determined way, in a fixed point of the petiole, and leaves a scar, being the right amputation.
Only in a few cases, and in the first place of the monocots, the fall occurs in an irregular way or by marcescence, such the palms.
At the base of the petiole, a layer of exchange cells determines the formation of the scar bearing; higher up is the real insulating layer in which tissue rupture occurs, followed in turn by a lignified layer. The scar bearing, at the point of detachment, is either lignified or suberised, or both phenomena co-occur.
In some dicotyledons, the structure of the detachment mechanism is complicated by the formation of the second layer of separation above the scar bearing, which shows an evolution of these issues since they do not appear concerning periodic seasonal factors, but as a consequence of traumatic or parasitic injuries, poisoning, etc.
In these cases, it is a question of a real expulsion of the leaves, as it has been demonstrated experimentally by subjecting the plant to sudden elevations of temperature or varying the concentration of anhydride of the surrounding air.
The leaves, before falling, get rid of most of the materials that can be useful to the plant: carbohydrates, protein substances, etc. The metabolism slag, such as excess salt, remains on the falling leaf, and in this way, the plant is exonerated from useless materials.