No matter how many trees there are on our planet, with various forms of crowns and foliage itself, they all care about one thing - cleaning the Earth's air from carbon dioxide, which humanity, the animal world, various equipment releases into the environment in unprecedented quantities. There is a lot of scientific and educational literature devoted to this particular section of botany - "Types of leaves". A person can change the appearance of a tree or shrub, giving it any, even the most bizarre, shape. But the types of leaves of trees and plants have remained unchanged for thousands of years.
Parts of the "body" of the sheet
Leaves are an integral part of the stem system of any tree, shrub or plant. The constituent parts of the leaf have their own names: blade, petiole, stipules.
The lamina is the largest part of the leaf, it is flat in appearance and has a variety of shapes, which we will discuss later.
Petiole is, in other words, a stalk, thanks to which the leaf plate is attached to the branch. Some plants have little or no petiole.
Stipules are the so-called appendages of the leaf, which are located at its base. Few people have seen and know this part of the sheet. The fact is that in most plants, stipules fall off even before the leafwill unfold completely. The only exceptions are some species, for example acacia.
In botany, various types of leaves are classified. Photos are below.
The most common are ordinary (or simple) leaves. These are types of leaves that consist of a single leaf blade. It can be either almost even, rounded, or dissected, multifaceted, like an oak or a potato. Simple leaves are divided into three subspecies: whole, lobed and dissected.
Plants having whole leaves
Speaking about the types of trees, it is worth mentioning first of all birches. No wonder this tree is a symbol of our country. Birch is widely distributed throughout the Northern Hemisphere of the Earth, but the largest concentration of these trees is located on the territory of Russia. Birch leaf - simple, solid, slightly curved, with a serrated edge. Plates of uniform green color, veins - in tone. In autumn, as you know, birch leaves turn yellow.
The same species also includes the foliage of another tree common in Russia - the apple tree. The leaf of this fruit tree is larger, but has the same characteristics: it is solid, slightly serrated along the edges, even in color.
Aspen, lilac, poplar, elm and other plants have exactly the same kind of leaf. However, only from a botanical point of view, they are similar to each other, external differences, of course, exist.
The second subspecies is lobed. This type of leaves is inherent in some maple trees. A living example is the leaf shown inCanadian flag. Leaves are classified as lobed if the "jags" on their edges do not exceed one-fourth of the total area.
This is exactly a bladed simple leaf. If you are seriously interested in the topic "Types of maple leaves", then the study can take many years. There are more than 50 species of these trees, each of which is notable not only for its habitat, but also for its appearance: from the height, the shape of the branches and trunk, and ending with the appearance of the leaves. We will not elaborate on this.
The third subspecies of simple leaves is dissected leaves. This species includes leaves that have cuts of more than one quarter of the leaf. For example, like a dandelion, tansy. Mostly this type is observed in medicinal plants and flowers.
Leaves with a complex structure
Types of leaves of trees and plants form the second large group - complex. They are called complex because they have several plates. They are conventionally divided into ternary, palmate and pinnate.
Representatives of the flora with trifoliate leaves - garden strawberries and wild strawberries, clover. Their distinguishing feature is three leaves on one petiole. The belief about the four-leaf clover has been passed down from generation to generation. It is not possible to find such a plant.
The leaves of horse chestnut, garden lupine are palmately complex.
To pinnate - raspberry leaves, mountain ash,peas. They also have their subspecies: the paired-pinnate ones are those where there are two leaves at the end of the stem, for example, like a pea, and the odd-pinnate ones are a rose, its petiole ends with one.
Types of plant leaves (plate shape)
Leaves are also classified according to the type of leaf plate:
1. Rounded.
These include such a houseplant as violet, as well as garden nasturtium, aspen.
2. Oval.
Leaf type found in elm, hazel.
3. Lanceolate.
Predominate in trees and shrubs of the willow family, as well as in a shrub called silver goof.
4. Ovate.
This name is given to the leaves of the well-known plantain
5. Linear.
This type of leaf is predominant in cereals, such as rye.
The shape of the leaf base is a separate feature for classification. Based on this setting. leaves come in:
- heart-shaped (like lilac);
- wedge-shaped (sorrel);
- arrow-shaped (arrowhead).
The shape of the top of the leaf is blunt, pointed, rounded, bilobed.
Separate topic - venation
Now consider how the venation affects the name of the leaf.
Dicotyledonous plants are characterized by reticulate venation. It is of two types: palmate (when all the veins come out like a bundle from one base) and pinnate (when smaller ones branch off from the main vein).
Monocot plants usually have a parallel or arcvenation. Parallel - in thinner leaves (leaves of wheat, reeds), arc - on wide sheets (lilies of the valley).
Some interesting facts about leaves
- The most delicate leaves are in a fern called maidenhair. There are simply no thinner ones in nature.
- The sharpest leaves are putang grass. The locals say that such grass is sharper than a knife.
- Cypress has over 45 million leaves.
- Welwitschia never grows more than two leaves.
- Victoria water lily has leaves over two meters in diameter.
- The length of the Raffia palm leaf is 20 meters.
- Not all plants drop leaves for the winter. There are those who call evergreens.
Types and color of leaves
Oddly enough, but the color of the sheet often does not envy either its shape or location. It's just that the color is inherent in the plant, that's all.
What makes up the color of a leaf? In summer, almost all plants are colored green due to the presence in their tissues of a special pigment - chlorophyll. This substance helps plants maintain their vitality, with its help the plant performs an unprecedented trick: during the daytime, it synthesizes glucose from carbon dioxide. In turn, glucose becomes the building block for all essential nutrients.
Why do leaves turn yellow?
In addition to chlorophyll, plant leaves contain other coloring substances, such as xanthophylls, carotene, anthocyanins. In the summer, their effect on colorsvery minimal, since the concentration of chlorophyll in plant tissues is thousands of times higher. But with the onset of autumn, all vital processes begin to fade, the amount of chlorophyll begins to decrease. It is noteworthy that it is under the light that cholorophyll is destroyed much faster. Therefore, if the autumn is sunny and warm, then the foliage turns yellow and falls faster.
