Complex sheet: structure, description, examples

All plants consist of vegetative and generative organs. The latter are responsible for reproduction. Angiosperms are a flower. He is a modified escape. The vegetative organs of a plant are the root system and shoots. The root system consists of the main root, lateral and additional. Sometimes the main root can be not expressed. Such a system is called friable. Shoots consist of stems, leaves and kidneys. Stems provide transport of substances, and also maintain the position of the plant. Kidneys are responsible for the formation of new shoots, as well as flowers. The leaf is the most important organ of the plant, since it is responsible for photosynthesis.

How it works

Simple and complex leaves consist of several types of tissues. Let's look at them in more detail.

From the point of view of histology

Above is the covering tissue - the epidermis. This layer is one-two thick with dense shells, located very close to each other. This fabric protects the sheet from mechanical damage, and also prevents excessive evaporation of water from the body. In addition, the epidermis participates in gas exchange. For this, a stomata is present in the tissue.

Above the epidermis is also an additional protective layer, which consists of wax, secreted by the cells of the integumentary tissue.

Under the layer of the epidermis there is a columnar, or assimilation parenchyma. This is the main tissue of the leaf. It is the process of photosynthesis. Parenchyma cells are located vertically. They contain a large number of chloroplasts.

Under the assimilation tissue is the conductive system of the leaf, as well as the spongy parenchyma. Conductive tissues are xylem and phloem. The first consists of vessels - dead cells, connected vertically with each other, without horizontal partitions. According to the xylem, water with substances dissolved in it enters the leaf from the root. Floema is composed of sieve tubes - long living cells. On this conductive tissue solutions are transported, on the contrary, from leaf to root.

Sponge fabric is responsible for gas exchange and evaporation of water.

Under the listed layers is the lower epidermis. He, like the upper one, performs a protective function. It also has a stomata.

Structure of leaves

From the stem leaves the petiole, on which the leaf blade is fastened - the main part of the leaf. From the petiole to the edges of the leaf veins. In addition, in its connections with the stem are stipules. Complex leaves, examples of which will be discussed below, are arranged in such a way that there are several leaf plates on one stalk.

What are the leaves

Depending on the structure, simple and complex leaves can be distinguished. Simple consists of a single plate. A complex sheet is one that consists of several plates. It can be varied in structure.

Types of complex leaves

There are several types. Factors for dividing them into species are the number of plates, the shape of the edges of the plates, and the shape of the sheet. There are five types.

Form sheet - what it is

There are such types:

• Arrow-shaped;
• Oval;
• Ring-shaped;
• Linear;
• Heart-shaped;
• Fan-shaped (semicircular sheet);
• Pointed;
• Needle-like;
• Wedge shaped (triangular leaf, attached to the stem on the top);
• Spear-shaped (sharp with spines);
• Shovel shaped;
• Blade (the leaf is divided into several blades);
• Lanceolate (long leaf wide in the middle);
• Back-lanceolate (the upper part of the leaf is wider than the lower one);
• Heart-shaped (heart-shaped leaf, fastened to the stalk with a sharp end);
• Rhomboid;
• Sickle-shaped.

A composite sheet can have plates of any of the listed forms.

Shape of the edges of plates

This is another factor that makes it possible to characterize a complex sheet.

Depending on the shape of the edges of the plates, leaves are of five types:

• Cogged;
• Citadel;
• Serrate;
• Vyemchatye;
• All-edged.

Other types of complex leaves

Depending on the number of plates and their location, the following types of complex leaves are distinguished:

• Fingered;
• Pinnate;
• Two-pinnate;
• Three-leaved;
• Perstonadreznye.

In fingered complex leaves, all plates radiate from the petiole, resembling fingers.

The leafy leaves have leaf blades along the petiole. They are divided into two types: parnoperistye and odd-pinnate. The first do not have the apical plate, their number is a multiple of two. In the nonparietal, the apical plate is present.

In bicarbonate leaves, the plates are located along the secondary petioles. The same, in turn, are attached to the main thing.

Three leaves have three plates.

Pinnatoon leaves are similar to pinnate.

Leaves are complex - their venation

There are three types:

• Parallel. The veins run smoothly from the base of the leaf to its edges along the entire plate.
• The arc. The veins go not exactly, but in the form of an arc.
• Mesh. It is divided into three subspecies: radial, palpate and peristhornous. With radial venation, the leaf has three major veins, from which the rest extend. Fingery is characterized by the presence of more than three major veins, which are separated near the base of the petiole. When peristonerous, the leaf has one major vein, from which the rest pass.

The most frequently complex sheet has a reticular venation.

Arrangement of leaves on the stem

Both simple and complex leaves can be arranged in different ways. There are four types of locations:

• Mulled. Leaves are fastened three times to a narrow stalk - a whorl. They can be crossed, with each whorl relative to the previous rotated by 90 degrees. Plants with such an arrangement of leaves are elodea, crow of the eye.
• Outlet. All leaves are at the same height and are arranged in a circle. Such rosettes have agave, chlorophytum.
• Consecutive (regular). The leaves are attached one by one to each knot. Thus, they are located near birch, pelargonium, apple, rose.
• The opposite. With this type of arrangement, there are two sheets on each node. Each node is usually rotated 90 degrees relative to the previous one. Also, the leaves can be arranged in two rows without turning the nodes. Examples of plants with this arrangement of leaves are peppermint, jasmine, lilac, fuchsia, glisten.

The first two types of leaf locations are characteristic of plants with simple leaves. But the second two species can refer to complex leaves.

Plant Examples

Now let's look at the different types of complex leaves with examples. They are allocated a sufficient amount. Plants with complex leaves can be of different life forms. It can be bushes and trees.

Very common plants with complex leaves - ash. These are trees of the olive family, the class of dicots, the department of angiosperms. They have odd-pinnate complex leaves, which have seven-fifteen plates. The shape of the edge is notched. Venation - mesh. Ash leaves are used in medicine as a diuretic.

A vivid example of a bush with complex leaves can be called a raspberry. These plants have nonparietal leaves with three to seven plates on long petioles. Type of venation - cirrus. The shape of the edge of the leaf is crenate. Raspberry leaves are also used in folk medicine. They contain substances that have an anti-inflammatory effect.

Another tree with complex leaves is mountain ash. Her leaves are parodermorous. The number of plates is about eleven. Venation - cirrus.

The next example is a clover. It has complex triple leaves. The venation of the clover is mesh. The shape of the edge of the sheet is one-piece. In addition to clover, triple leaves also have a bean.

Complex plants also have plants such as albicans. It has bicritate leaves.

Another bright example of a plant with complex leaves is acacia. This bush has a reticular venation. The shape of the edge is one-piece. Type of sheet - two-pinnate. Number of plates - from eleven pieces.

Another plant with complex leaves is strawberry. Sheet type - three-sheeted. Venation - mesh. These leaves are also used in folk medicine. Usually with atherosclerosis and other vascular diseases.

Conclusion

As an output, we give a generalizing table on complex leaves.

So we examined the structure of a complex leaf, its types, examples of plants that they possess.