Fibrous root system examples of plants. Fibrous root system: structural features and functions

The roots of a plant are its vegetative organs, located underground and conducting water and, accordingly, minerals to the rest, above-ground, organs of the plant - stems, leaves, flowers and fruits. But the main function of the root is still to anchor the plant in the soil.

About the distinctive features of root systems

What is common in different root systems is that the root is always divided into main, lateral and subordinate ones. The main root, the root of the first order, always grows from a seed; it is the one that is most powerfully developed and always grows vertically downwards.

The lateral roots extend from it and are called roots of the second order. They can branch, and adventitious roots, called third-order roots, extend from them. They (adventitious roots) never grow on the main root, but in some plant species they can grow on stems and leaves.

This entire collection of roots is called the root system. And there are only two types of root systems - taproot and fibrous. And our main question concerns the difference between taproot and fibrous root systems.

The taproot system is characterized by the presence of a clearly defined main root, while the fibrous root system is formed from adventitious and lateral roots, and its main root is not pronounced and does not stand out from the general mass.

To better understand how the taproot system differs from the fibrous one, we propose to consider a visual diagram of the structure of the first and second systems.

Plants such as roses, peas, buckwheat, valerian, carrots, maple, birch, currants, and watermelon have a tap root system. Wheat, oats, barley, onions and garlic, lilies, gladiolus and others have a fibrous root system.

Modified shoots underground

Many plants have so-called modified shoots underground in addition to roots. These are rhizomes, stolons, bulbs and tubers.

Rhizomes grow mainly parallel to the soil surface; they are needed for vegetative propagation and storage. Externally, the rhizome is similar to the root, but in its internal structure it has fundamental differences. Sometimes such shoots can come out of the ground and form a regular shoot with leaves.

Stolons are underground shoots, at the end of which bulbs, tubers and rosette shoots are formed.

A bulb is a modified shoot, the storage function of which is carried out by fleshy leaves, and adventitious roots extend from the flat bottom below.

A tuber is a thickened shoot with axillary buds that performs the function of storage and reproduction.

Phylogenetically, the root arose later than the stem and leaf - in connection with the transition of plants to life on land and probably originated from root-like underground branches. The root has neither leaves nor buds arranged in a certain order. It is characterized by apical growth in length, its lateral branches arise from internal tissues, the growth point is covered with a root cap. The root system is formed throughout the life of the plant organism. Sometimes the root can serve as a storage site for nutrients. In this case, it changes.

Types of roots

The main root is formed from the embryonic root during seed germination. Lateral roots extend from it.

Adventitious roots develop on stems and leaves.

Lateral roots are branches of any roots.

Each root (main, lateral, adventitious) has the ability to branch, which significantly increases the surface of the root system, and this helps to better strengthen the plant in the soil and improve its nutrition.

Types of root systems

There are two main types of root systems: taproot, which has a well-developed main root, and fibrous. The fibrous root system consists of a large number of adventitious roots, equal in size. The entire mass of roots consists of lateral or adventitious roots and has the appearance of a lobe.

The highly branched root system forms a huge absorbing surface. For example,

• the total length of winter rye roots reaches 600 km;
• length of root hairs - 10,000 km;
• the total root surface is 200 m2.

This is many times the area of ​​the aboveground mass.

If the plant has a well-defined main root and adventitious roots develop, then a mixed type root system (cabbage, tomato) is formed.

External structure of the root. Internal structure of the root

Root zones

Root cap

The root grows in length from its apex, where the young cells of the educational tissue are located. The growing part is covered with a root cap, which protects the root tip from damage and facilitates the movement of the root in the soil during growth. The latter function is carried out due to the property of the outer walls of the root cap being covered with mucus, which reduces friction between the root and soil particles. They can even push soil particles apart. The cells of the root cap are living and often contain starch grains. The cells of the cap are constantly renewed due to division. Participates in positive geotropic reactions (direction of root growth towards the center of the Earth).

The cells of the division zone are actively dividing; the extent of this zone varies in different species and in different roots of the same plant.

Behind the division zone is an extension zone (growth zone). The length of this zone does not exceed a few millimeters.

As linear growth completes, the third stage of root formation begins—its differentiation; a zone of cell differentiation and specialization (or a zone of root hairs and absorption) is formed. In this zone, the outer layer of the epiblema (rhizoderm) with root hairs, the layer of the primary cortex and the central cylinder are already distinguished.

Root hair structure

Root hairs are highly elongated outgrowths of the outer cells covering the root. The number of root hairs is very large (per 1 mm2 from 200 to 300 hairs). Their length reaches 10 mm. Hairs form very quickly (in young apple tree seedlings in 30-40 hours). Root hairs are short-lived. They die off after 10-20 days, and new ones grow on the young part of the root. This ensures the development of new soil horizons by the roots. The root continuously grows, forming more and more new areas of root hairs. Hairs can not only absorb ready-made solutions of substances, but also contribute to the dissolution of certain soil substances and then absorb them. The area of ​​the root where the root hairs have died is able to absorb water for a while, but then becomes covered with a plug and loses this ability.

The hair shell is very thin, which facilitates the absorption of nutrients. Almost the entire hair cell is occupied by a vacuole, surrounded by a thin layer of cytoplasm. The nucleus is at the top of the cell. A mucous sheath is formed around the cell, which promotes the gluing of root hairs to soil particles, which improves their contact and increases the hydrophilicity of the system. Absorption is facilitated by the secretion of acids (carbonic, malic, citric) by root hairs, which dissolve mineral salts.

Root hairs also play a mechanical role - they serve as support for the root tip, which passes between the soil particles.

Under a microscope, a cross section of the root in the absorption zone shows its structure at the cellular and tissue levels. On the surface of the root there is rhizoderm, under it there is bark. The outer layer of the cortex is the exodermis, inward from it is the main parenchyma. Its thin-walled living cells perform a storage function, conducting nutrient solutions in a radial direction - from the suction tissue to the vessels of the wood. They also contain the synthesis of a number of organic substances vital for the plant. The inner layer of the cortex is the endoderm. Nutrient solutions entering the central cylinder from the cortex through endodermal cells pass only through the protoplast of cells.

The bark surrounds the central cylinder of the root. It borders on a layer of cells that retain the ability to divide for a long time. This is a pericycle. Pericycle cells give rise to lateral roots, adventitious buds and secondary educational tissues. Inward from the pericycle, in the center of the root, there are conductive tissues: bast and wood. Together they form a radial conductive bundle.

The root vascular system conducts water and minerals from the root to the stem (upward current) and organic matter from the stem to the root (downward current). It consists of vascular-fibrous bundles. The main components of the bundle are sections of phloem (through which substances move to the root) and xylem (through which substances move from the root). The main conducting elements of phloem are sieve tubes, xylem is trachea (vessels) and tracheids.

Root life processes

Transport of water in the root

Absorption of water by root hairs from the soil nutrient solution and conduction of it in a radial direction along the cells of the primary cortex through passage cells in the endoderm to the xylem of the radial vascular bundle. The intensity of water absorption by root hairs is called suction force (S), it is equal to the difference between osmotic (P) and turgor (T) pressure: S=P-T.

When the osmotic pressure is equal to the turgor pressure (P=T), then S=0, water stops flowing into the root hair cell. If the concentration of substances in the soil nutrient solution is higher than inside the cell, then water will leave the cells and plasmolysis will occur - the plants will wither. This phenomenon is observed in conditions of dry soil, as well as with excessive application of mineral fertilizers. Inside the root cells, the suction force of the root increases from the rhizoderm towards the central cylinder, so water moves along a concentration gradient (i.e. from a place with a higher concentration to a place with a lower concentration) and creates root pressure, which raises the column of water through the xylem vessels , forming an ascending current. This can be found on leafless trunks in the spring when the “sap” is collected, or on cut stumps. The flow of water from wood, fresh stumps, and leaves is called “crying” of plants. When the leaves bloom, they also create a suction force and attract water to themselves - a continuous column of water is formed in each vessel - capillary tension. Root pressure is the lower driver of water flow, and the suction force of the leaves is the upper one. This can be confirmed using simple experiments.

Absorption of water by roots

Target: find out the basic function of the root.

What we do: plant grown on wet sawdust, shake off its root system and lower its roots into a glass of water. To protect it from evaporation, pour a thin layer of vegetable oil on top of the water and mark the level.

What we see: After a day or two, the water in the container dropped below the mark.

Result: consequently, the roots sucked up the water and brought it up to the leaves.

You can also do one more experiment to prove the absorption of nutrients by the root.

What we do: cut off the stem of the plant, leaving a stump 2-3 cm high. We put a rubber tube 3 cm long on the stump, and on the upper end we put a curved glass tube 20-25 cm high.

What we see: The water in the glass tube rises and flows out.

Result: this proves that the root absorbs water from the soil into the stem.

Does water temperature affect the intensity of water absorption by roots?

Target: find out how temperature affects root function.

What we do: one glass should be with warm water (+17-18ºС), and the other with cold water (+1-2ºС).

What we see: in the first case, water is released abundantly, in the second - little, or stops altogether.

Result: this is proof that temperature greatly influences root function.

Warm water is actively absorbed by the roots. Root pressure increases.

Cold water is poorly absorbed by the roots. In this case, root pressure drops.

Mineral nutrition

The physiological role of minerals is very great. They are the basis for the synthesis of organic compounds, as well as factors that change the physical state of colloids, i.e. directly affect the metabolism and structure of the protoplast; act as catalysts for biochemical reactions; affect cell turgor and protoplasm permeability; are centers of electrical and radioactive phenomena in plant organisms.

It has been established that normal plant development is possible only if there are three non-metals in the nutrient solution - nitrogen, phosphorus and sulfur and four metals - potassium, magnesium, calcium and iron. Each of these elements has an individual meaning and cannot be replaced by another. These are macroelements, their concentration in the plant is 10 -2 -10%. For normal plant development, microelements are needed, the concentration of which in the cell is 10 -5 -10 -3%. These are boron, cobalt, copper, zinc, manganese, molybdenum, etc. All these elements are present in the soil, but sometimes in insufficient quantities. Therefore, mineral and organic fertilizers are added to the soil.

The plant grows and develops normally if the environment surrounding the roots contains all the necessary nutrients. This environment for most plants is soil.

Breathing of roots

For normal growth and development of the plant, fresh air must be supplied to the roots. Let's check if this is true?

Target: Does the root need air?

What we do: Let's take two identical vessels with water. Place developing seedlings in each vessel. Every day we saturate the water in one of the vessels with air using a spray bottle. Pour a thin layer of vegetable oil onto the surface of the water in the second vessel, as it delays the flow of air into the water.

What we see: After some time, the plant in the second vessel will stop growing, wither, and eventually die.

Result: The death of the plant occurs due to a lack of air necessary for the root to breathe.

Root modifications

Some plants store reserve nutrients in their roots. They accumulate carbohydrates, mineral salts, vitamins and other substances. Such roots grow greatly in thickness and acquire an unusual appearance. Both the root and the stem are involved in the formation of root crops.

Roots

If reserve substances accumulate in the main root and at the base of the stem of the main shoot, root vegetables (carrots) are formed. Plants that form root crops are mostly biennials. In the first year of life, they do not bloom and accumulate a lot of nutrients in the roots. On the second, they quickly bloom, using the accumulated nutrients and forming fruits and seeds.

Root tubers

In dahlia, reserve substances accumulate in adventitious roots, forming root tubers.

Bacterial nodules

The lateral roots of clover, lupine, and alfalfa are peculiarly modified. Bacteria settle in young lateral roots, which promotes the absorption of gaseous nitrogen from the soil air. Such roots take on the appearance of nodules. Thanks to these bacteria, these plants are able to live in nitrogen-poor soils and make them more fertile.

Stilates

Ramp, which grows in the intertidal zone, develops stilted roots. They hold large leafy shoots on unstable muddy soil high above the water.

Air

Tropical plants living on tree branches develop aerial roots. They are often found in orchids, bromeliads, and some ferns. Aerial roots hang freely in the air without reaching the ground and absorb moisture from rain or dew that falls on them.

Retractors

In bulbous and corm plants, such as crocuses, among the numerous thread-like roots there are several thicker, so-called retractor roots. By contracting, such roots pull the corm deeper into the soil.

Columnar

Ficus plants develop columnar above-ground roots, or supporting roots.

Soil as a habitat for roots

Soil for plants is the medium from which it receives water and nutrients. The amount of minerals in the soil depends on the specific characteristics of the parent rock, the activity of organisms, the life activity of the plants themselves, and the type of soil.

Soil particles compete with roots for moisture, retaining it on their surface. This is the so-called bound water, which is divided into hygroscopic and film water. It is held in place by the forces of molecular attraction. The moisture available to the plant is represented by capillary water, which is concentrated in the small pores of the soil.

An antagonistic relationship develops between moisture and the air phase of the soil. The more large pores there are in the soil, the better the gas regime of these soils, the less moisture the soil retains. The most favorable water-air regime is maintained in structural soils, where water and air exist simultaneously and do not interfere with each other - water fills the capillaries inside the structural units, and air fills the large pores between them.

The nature of the interaction between plant and soil is largely related to the absorption capacity of the soil - the ability to hold or bind chemical compounds.

Soil microflora decomposes organic matter into simpler compounds and participates in the formation of soil structure. The nature of these processes depends on the type of soil, the chemical composition of plant residues, the physiological properties of microorganisms and other factors. Soil animals take part in the formation of soil structure: annelids, insect larvae, etc.

As a result of a combination of biological and chemical processes in the soil, a complex complex of organic substances is formed, which is combined with the term “humus”.

Water culture method

What salts the plant needs, and what effect they have on its growth and development, was established through experience with aquatic crops. The water culture method is the cultivation of plants not in soil, but in an aqueous solution of mineral salts. Depending on the goal of the experiment, you can exclude a particular salt from the solution, reduce or increase its content. It was found that fertilizers containing nitrogen promote plant growth, those containing phosphorus promote the rapid ripening of fruits, and those containing potassium promote the rapid outflow of organic matter from leaves to roots. In this regard, it is recommended to apply fertilizers containing nitrogen before sowing or in the first half of summer; those containing phosphorus and potassium - in the second half of summer.

Using the water culture method, it was possible to establish not only the plant’s need for macroelements, but also to clarify the role of various microelements.

Currently, there are cases where plants are grown using hydroponics and aeroponics methods.

Hydroponics is the growing of plants in containers filled with gravel. A nutrient solution containing the necessary elements is fed into the vessels from below.

Aeroponics is the air culture of plants. With this method, the root system is in the air and is automatically (several times within an hour) sprayed with a weak solution of nutrient salts.

Laboratory work “Tap and fibrous root systems”

• 1. form the concepts of taproot and fibrous root systems;
• 2. develop the skill of distinguishing between taproot and fibrous root systems;
• 3. continue to develop the skills to observe natural objects.

Equipment: herbarium specimens of plants of the local flora with fibrous and tap root systems.

The work is carried out according to the instruction card on p. 90-91 of the textbook “Biology” by V.V. Pasechnik and is written in a workbook as task 63.

Consolidation of what has been learned.

• 1Questions:
• 1) What functions does the root perform?
• 2) What types of roots does the root system consist of?
• 3) What is the structure of the tap root system?
• 4) How does a fibrous root system differ from a tap root system?
• 5) What is the basis for the use of plants to secure ravines, screes, and river banks?
• 6) What is the importance of adventitious roots for increasing yield?
• 7) What is the importance of knowledge about the structure of the root for controlling the growth and development of agricultural plants?
• 2. Fill out the table.

(Students fill out the column “Definition of concepts” independently).

Basic Concepts	Definition of concepts
	Underground organs of plants that absorb water and mineral salts, holding the plant in the soil
2. Root system	System of all plant roots
3. Main root	The root that goes deepest into the soil
4. Lateral roots	Roots extending from the sides of the main and adventitious roots
5. Adventitious roots	Roots extending from the sides of the stem
6. Tap root system	Root system consisting of main and lateral roots
7. Fibrous root system	Root system consisting of adventitious and lateral roots

4. Homework assignment. Study paragraph 19, complete task 64 in the workbook: what agricultural technique is shown in the picture? For what purpose is it used? (1 level)

• Level 2. Answer the questions: 1. The total surface of the roots of sushi plants is approximately 150 times greater than the surface of its aboveground part. What does this mean for plants?
• 2) Why is it believed that plants with fibrous root systems protect the soil from erosion?
• 3) How does a root differ from a shoot? 4) How do plant nutrition differ from animal nutrition?
• Level 3:
• 1) Model the evolutionary development of the root system.
• 2) Due to erosion alone, 7 million hectares of land lose their fertility every year. What erosion control measures would you suggest?

Plan of experimental work at the school educational and experimental site of the municipal educational institution of general education in the village of Akatnaya Maza for the 2009-2010 academic year

The area of ​​the school educational and experimental site is 0.84 hectares.

The site has a uniform soil composition. Soil of the site quite fertile.

The school educational and experimental site has the following departments:

• 1. Department of vegetable crops in the row crop rotation system;
• 2. Department of field crops in the grass crop rotation system;
• 3. Department of ornamental plants;
• 4. Experienced department;
• 5. Department of Plant Biology:
  • a) area of ​​plant taxonomy;
  • b) plant collection area;
• 6. Department of protected soil (greenhouses);
• 7. Dendrological department;
• 8. Primary school department.

Calendar and agrotechnical plan at the school training and experimental site

	Name of events	Deadlines
	Cover harrowing
	Fine digging of the soil (8-10 cm).
	Dividing the site into sections and plots.
	Vernalization of potato tubers.
	Soil preparation on plots for field grain crops.
	Sowing early grain crops.
	Sowing sunflowers, carrots, red beets.
	Sowing crops at the Department of Plant Biology.
	Preparing the soil in the collection department.
	Sowing of early crops in the collection department.
	Sowing vegetable seeds in a cold nursery.
	Sowing corn.
	Sowing flower seeds in beds to obtain seedlings.
	Laying out plots on the experimental plot.
	Sowing beans, chamomile.
	Preparation of pumpkin and zucchini seeds (soaking, germination).
	Planting pumpkins, zucchini, squash.
	Sowing cucumbers.
	Making holes in vegetable crop rotation and experimental ones (for cabbage, tomatoes).
	Planting vegetables.
	Laying out the flower bed.
	Planting flowers in the school grounds, near the monument.
	Caring for agricultural crops during the growing season (loosening, weeding, fertilizing, watering, pest and disease control, conducting experiments), thinning, planting, shelter from spring frosts, hilling row crops, additional artificial pollination of sunflower and corn, weed control, preparation plots for winter crops, destruction of weeds, preparation of plots for winter crops, selection of large seeds, sowing seeds of winter rye and wheat, caring for seedlings, harvesting crops, selling the resulting products. Basic tillage - fertilization, digging.	During the growing season.

Experimental work at the school educational and experimental site.

Theme of the experiment: “The influence of foliar feeding on the yield

cabbage variety "Slava"

Purpose of the experiment: to find out the effect of foliar feeding on

crop harvest (cabbage).

The experiment is carried out by 6th grade students.

Team composition:

Elesin Alyosha,

Safonova, Yana

Slavkina Ksyusha,

Ryabova Olya.

Methodology for conducting the experiment.

Foliar feeding is feeding plants directly through the leaves. By spraying them with weak solutions containing nutrients, experience has established that the nutrients applied to the leaves during foliar feeding are used not only by these leaves, but by the entire plant.

With foliar feeding, the utilization rate of nutrients from fertilizers significantly increases, since the latter enter directly into the leaf tissue, bypassing the soil, where usually most of these nutrients are lost.

Cabbage, as a leaf crop, responds very well to nitrogen fertilizers. For 10 liters of water, take 150 g of ammonium nitrate; 15-20 days after planting the seedlings in open ground, apply the first foliar feeding. Repeat during the summer 5-6 times at intervals of 7-10 days.

Root system all the roots of a plant are called. It is formed by the main root, lateral roots and adventitious roots. The main root of a plant develops from a germinal root. Adventitious roots usually grow from the lower parts of the plant stem. Lateral roots develop on the main and adventitious roots.

The root system of plants performs two main functions.

Firstly, it holds the plant in the soil. Secondly, the roots absorb from the soil the water and minerals dissolved in it that the plant needs.

If a plant develops a powerful main root, it forms taproot system.

If the main root remains undeveloped or dies, and adventitious roots develop, then the plant develops fibrous root system.

The taproot system is characterized by a well-developed main root.

In appearance it looks like a rod. The main root grows from the embryonic root.

The taproot system is formed not only by the main root, but also by small lateral roots extending from it.

The tap root system is characteristic of many dicotyledonous plants.

Beans, clover, sunflower, carrots, and dandelion have a well-developed main root.

However, in many perennial plants with an original taproot system, the taproot eventually dies. Instead, numerous adventitious roots grow from the stem.

There is a subtype of tap root system - branched root system.

In this case, several lateral roots receive strong development. While the main root remains shortened. The type of branched root system is characteristic of many trees. This root system allows you to firmly hold the powerful trunk and crown of the tree.

The tap root system penetrates deeper into the soil than the fibrous root system.

Fibrous type of root system

A fibrous root system is characterized by the presence of many approximately identical adventitious roots, which form a kind of bundle.

Adventitious roots grow from aboveground and underground parts of the stem, less often from leaves.

Plants with fibrous root systems may also have a living main root. However, if it is preserved, it does not differ in size from the other roots.

A fibrous root system is characteristic of many monocots. Among them are wheat, rye, onions, garlic, corn, potatoes.

Although the fibrous root system does not penetrate the soil as deeply as the tap root system, it occupies a larger area at the soil surface and more tightly entwines soil particles, which improves the absorption of the aqueous solution.

Root systems and their classification. Types of root systems

Root modifications:

Root vegetable - thickened main root.

The main root and the lower part of the stem are involved in the formation of the root crop.

Most root plants are biennial. Root vegetables consist mainly of storage tissue (turnips, carrots, parsley).

Root tubers (root cones) are formed as a result of thickening of the lateral and adventitious roots.

With their help, the plant blooms faster.

Hook roots are a kind of adventitious roots. With the help of these roots, the plant “glues” to any support.

Stilt roots act as a support.

Board-shaped roots are lateral roots that extend close to or above the soil surface, forming triangular vertical outgrowths adjacent to the trunk. Characteristic of large trees of tropical rain forest.

Aerial roots are lateral roots that grow in the aboveground part.

Absorb rainwater and oxygen from the air. They are formed in many tropical plants under conditions of a lack of mineral salts in the soil of the tropical forest.

Mycorrhiza is the cohabitation of the roots of higher plants with fungal hyphae. With such mutually beneficial cohabitation, called symbiosis, the plant receives water with nutrients dissolved in it from the fungus, and the fungus receives organic substances.

Mycorrhiza is characteristic of the roots of many higher plants, especially woody ones. Fungal hyphae, entwining the thick lignified roots of trees and shrubs, perform the functions of root hairs.

Bacterial nodules on the roots of higher plants - the cohabitation of higher plants with nitrogen-fixing bacteria - are modified lateral roots adapted to symbiosis with bacteria.

Bacteria penetrate through the root hairs into young roots and cause them to form nodules. With this symbiotic cohabitation, bacteria convert nitrogen contained in the air into a mineral form available to plants.

And plants, in turn, provide bacteria with a special habitat in which there is no competition with other types of soil bacteria. Bacteria also use substances found in the roots of higher plants.

More often than others, bacterial nodules form on the roots of plants of the legume family. Due to this feature, legume seeds are rich in protein, and members of the family are widely used in crop rotation to enrich the soil with nitrogen.

Respiratory roots - in tropical plants - perform the function of additional respiration.

Types of root systems

In the tap root system, the main root is highly developed and clearly visible among other roots (typical of dicotyledons).

A type of tap root system is a branched root system: it consists of several lateral roots, among which the main root is not distinguished; characteristic of trees.

In the fibrous root system, at the early stages of development, the main root, formed by the embryonic root, dies, and the root system is composed of adventitious roots (typical of monocots). The taproot system usually penetrates deeper into the soil than the fibrous root system, but the fibrous root system weaves better around adjacent soil particles.

Adventitious roots grow directly from the stem.

They grow from a bulb (which is a special stem) or from garden cuttings.

Aerial roots. Roots that grow from the stem but do not penetrate the ground.

They are used by climbing plants for anchorage, such as ivy.

Supporting (stilted) roots.

A special type of aerial roots. They grow from a stem and then penetrate the ground, which may be covered with water. They support heavy plants such as mangroves.

Related information:

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How does a tap root system differ from a fibrous root system?

The roots of a plant are its vegetative organs, located underground and conducting water and, accordingly, minerals to the rest, above-ground, organs of the plant - stems, leaves, flowers and fruits.

But the main function of the root is still to anchor the plant in the soil.

About the distinctive features of root systems

What is common in different root systems is that the root is always divided into main, lateral and subordinate ones.

The main root, the root of the first order, always grows from a seed; it is the one that is most powerfully developed and always grows vertically downwards.

The lateral roots extend from it and are called roots of the second order. They can branch, and adventitious roots, called third-order roots, extend from them.

They (adventitious roots) never grow on the main root, but in some plant species they can grow on stems and leaves.

This entire collection of roots is called the root system. And there are only two types of root systems - taproot and fibrous. And our main question concerns the difference between taproot and fibrous root systems.

The taproot system is characterized by the presence of a clearly defined main root, while the fibrous root system is formed from adventitious and lateral roots, and its main root is not pronounced and does not stand out from the general mass.

To better understand how the taproot system differs from the fibrous one, we propose to consider a visual diagram of the structure of the first and second systems.

Plants such as roses, peas, buckwheat, valerian, parsley, carrots, maple, birch, currants, and watermelon have a taproot system.

Wheat, oats, barley, onions and garlic, lilies, gladiolus and others have a fibrous root system.

Modified shoots underground

Many plants have so-called modified shoots underground in addition to roots. These are rhizomes, stolons, bulbs and tubers.

Rhizomes grow mainly parallel to the soil surface; they are needed for vegetative propagation and storage. Externally, the rhizome is similar to the root, but in its internal structure it has fundamental differences.

Sometimes such shoots can come out of the ground and form a regular shoot with leaves.

Stolons are underground shoots, at the end of which bulbs, tubers and rosette shoots are formed.

A bulb is a modified shoot, the storage function of which is carried out by fleshy leaves, and adventitious roots extend from the flat bottom below.

A tuber is a thickened shoot with axillary buds that performs the function of storage and reproduction.

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Superficial root system

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A superficial root system is also formed in pine when dense, heavy carbonate loam is located shallowly, and on such soils windfall of pine seed plants and sometimes larch seed plants is often observed. This phenomenon occurs, for example, in a number of places in the Plesetsk district of the Arkhangelsk region. On the Kola Peninsula (Murmansk region), windfall of pine seed plants is expressed in places where crystalline rocks emerge on the day surface.

The superficial root system of pine, as we have already said, is also formed when dense, heavy carbonate loam is located shallowly. On such soils, pine seeds and sometimes larch seeds often fall out with the wind, for example, in some places in the Plesetsk district of the Arkhangelsk region.

On the Kola Peninsula (Murmansk region) and in North Karelia, windfall of pine seeds occurs in places where crystalline rocks emerge on the day surface.

A shallow root system with weak development of vertically developing roots, only 0 5 - 1 m deep, is formed by pine on sandy soils poor in moisture, where it can also fall out relatively easily from the wind.

Trees with a shallow root system are more susceptible to wind blows, are more weakened and more often die off while still standing.

The disproportion between increased transpiration after felling and the limited supply of moisture from the soil, as well as ruptures of small roots due to the swaying of trees by the wind, lead to a decrease in growth in shallow, heavy, moist soils immediately after cutting. On the contrary, trees on deep-drained soils, where they form roots that go deep into the soil and are better provided with moisture, can withstand changing conditions relatively well and are able to increase their growth in diameter after 2-3 years, and sometimes immediately after cutting.

These differences are also reflected in the anatomical structure of the tree.

Trees with a shallow root system are more susceptible to wind blows, are more weakened and more often die off at the root.

The superficial root system of spruce, damaged by livestock hooves, is not able to resist the honey fungus.

There are known facts of the impact of wind, when windfalls caused the destruction of PTCs with weakened drainage, forming a superficial root system of trees and located in wind-prone locations.

Windfall often develops in the PTC of spruce forests on accumulative slopes with rich, moist loams, where the spruce has a thin superficial root system. Tree stands of PTC on denudation slopes with boulder-stone substrates, where spruce is firmly rooted in the crevices of blocks, are more wind-resistant.

Even low-level fire destroys thin-barked spruce and fir, with a crown that descends low along the trunk, with a thinner-barked surface root system, and thus immediately removes two main obstacles to the emergence of self-seeding pine.

Old pine trees have a chance of surviving any fire due to their thicker bark, highly raised crown and root system going very deep into the soil; these old trees remain scattered as seed plants in greater or lesser numbers even after severe fires.

After flowering, the plants are transplanted into wide and shallow pots or bowls, since azaleas have a superficial root system, pruning is carried out, removing weak, fattening shoots and pinching the tops of young shoots, stimulating their branching. Pinching is carried out in two or three steps, pinching shoots with three to four developed leaves. At the end of June, pinching is stopped, since at this time the formation of next year's flower buds begins on the shoots.

Azaleas need moist air. During the period of active growth, from March to September, they are regularly sprayed with soft water. It is not recommended to spray during the flowering period to avoid the appearance of spots on the flowers. For normal flowering, high light intensity and fertilizing with complex fertilizer are needed.

Weymouth pine is a relatively wind-resistant species, but, like common pine, it can also produce a shallow root system, for example on shallow soils. Weymouth pine is no less sensitive to factory smoke than ordinary pine.

Large areas of underground structures, embanked with a sufficient layer of earth, are landscaped with small groups of shrubs with a superficial root system or perennials.

If decorative decoration is necessary, small rockeries are arranged on them. To avoid icing, trees and shrubs should be planted at a distance of at least 40 m from open sprinkler devices, and from cooling towers at a distance of at least 15 of their height.

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Root

The root performs the function of absorbing water and minerals from the soil. It anchors and holds the plant in the soil. Spare nutrients can be deposited in the roots.

Root structure

The root is the axial organ of the plant, which, unlike the stem, does not have leaves. The root grows in length throughout the life of the plant, moving among solid soil particles. To protect the delicate root tip from mechanical damage and reduce friction, a root cap is used.

It is formed by thin-walled cells of the integumentary tissue, which peel off and form mucus, which facilitates the movement of the root in the soil. The growing root's sheath is renewed every day.

Under the root cap there is a division zone. It consists of educational fabric.

The cells of this tissue divide.

The resulting cells stretch in the longitudinal direction and form a zone of stretching and growth. This ensures the root grows in length. Cells of educational tissue form other tissues - integumentary, conductive and mechanical.

The tension zone is followed by the suction zone.

In this zone, many root hairs are formed from the cells of the integumentary tissue. In wheat, for example, there are up to 100 of them per 1 mm2 of root surface. Thanks to root hairs, the suction surface of the root increases tens and even hundreds of times. Root hairs work like tiny pumps that suck water with dissolved minerals from the soil. The suction zone is mobile; it changes its place in the soil depending on the growth of the root. Root hairs live for several days and then die, and a suction zone appears on the newly growing section of the root.

Therefore, the absorption of water and nutrients always occurs from a new volume of soil.

In place of the previous absorption zone, a conduction zone is formed. Water and minerals are carried upward through the cells of this zone, to the above-ground organs, and organic substances are carried downwards, from the leaves to the roots.

Cells of the integumentary tissue of the conduction zone in adult plants, when dying, can be layered on top of each other, forming a plug. As a result, the adult root becomes lignified.

The conduction zone accounts for most of the length of long-lived roots.

Types of root systems

The totality of all the roots of a plant is called the root system. There are two types of root systems - taproot and fibrous.

In the taproot system, the main root is distinguished.

It grows straight down and stands out among other roots by being longer and thicker. Lateral roots extend from the main root. The taproot system is characteristic of peas, sunflowers, shepherd's purse, dandelion and many other plants.

The fibrous root system is characteristic of cereals, plantain and other plants in which the main root stops growing immediately at the beginning of embryo development.

In this case, numerous roots are formed at the base of the shoot, which are called adventitious.

The plant develops a bunch, or lobe, of adventitious roots more or less equal in thickness, length and branching.

The root, being the most important organ, performs a number of irreplaceable functions and is quite diverse in its structural features. Without it, the life of plant organisms would be practically impossible. Our article will examine in detail the fibrous plant in which plants it develops, what characteristic features it has and how it helps organisms adapt to constantly changing environmental conditions.

What is a root

A root is an underground organ of a plant. Obviously, in plants it is not singular. Indeed, all the roots of one organism differ in appearance and developmental features. There are three types of underground parts of plants: main, lateral and accessory. It won't be difficult to distinguish them. The plant always has one main root. It stands out from the rest in size and length. Lateral roots grow on it. They are quite numerous. And if the roots grow directly from the shoot, then they are adventitious.

Root functions

Without a root, the plant will die, since its functions are truly vital. First of all, it is the fixation of organisms in the soil, providing mineral nutrition and upward flow of water. If necessary, many plants form For example, beets, carrots and radishes form root vegetables. These are thickenings of the main root. They accumulate water and a supply of necessary substances to survive unfavorable conditions.

Types of root systems

One type of root is not enough for a plant. After all, the life of the entire organism depends on the functioning of this organ. Therefore, the plant develops root systems consisting of several types of underground organs. They are more efficient. The main types of root systems are taproot and fibrous. Their main difference lies in their structural features. For example, a fibrous root system is characterized by a small depth of penetration, while a tap root system, on the contrary, allows plants to receive water from considerable depths.

Tap root system

The very name of this structure characterizes the features of its structure. It has a pronounced main root. This is how the taproot system differs from the fibrous one. Thanks to this, plants with this structure are able to obtain water from a depth of several tens of meters. Lateral roots extend from the main root, which increases the absorption surface.

Structure of the fibrous root system

The fibrous root system consists of only one type of roots - adventitious ones. They grow directly from the above-ground part of the plant, so they form a bunch. Usually they are all the same length. Moreover, the main root still grows at the beginning of development. However, it subsequently dies off. As a result, only those roots that grow from the shoot itself remain. In most cases, such a beam is quite powerful. Try to pull a wheat plant out of wet soil with your hands and you will see that this requires considerable force. Sometimes lateral roots can develop on adventitious roots, which further increases the diameter occupied by this system.

Which plants have a fibrous root system?

In the process of evolution, this structure first appears in representatives of higher spore plants - ferns, mosses and horsetails. Since in most of them the body is represented by an underground modification of the shoot, namely a rhizome, adventitious roots grow from it. This is a big step forward in the phylogeny of plant organisms, since algae and other representatives of spores had only rhizoids. These formations had no tissue and performed only the function of attachment to the substrate.

All plants that belong to the class Monocots also have. Along with the absence of cambium, arched or other features, this is their systematic feature. This class is represented by several families. For example, Liliaceae and Onions form a characteristic thickened underground stem in which water and all the necessary minerals are stored. It's called an onion. Bunches of adventitious roots grow from it. Rice, wheat, corn, rye, barley are representatives. They are also characterized by a fibrous root system. Examples of this structure are also dahlia, asparagus, sweet potato, and chistyak. Their adventitious roots are significantly thickened and take on a tuberous shape. They also store nutrients. Such modifications are called root tubers. Supporting, breathing, suckers and trailers also grow from the shoot. Therefore, they can also be considered a modification of the fibrous root system. For example, vines with the help of trailing roots can grow even on a vertical surface. And orchids absorb moisture directly from the air. This is carried out by adventitious respiratory roots. A special modification occurs in corn. These are support roots. They surround the lower part of the stem and support a powerful shoot with heavy fruit-cobs.

Advantages and disadvantages of fibrous root system

Plants that do not have to obtain moisture from a significant depth have a fibrous root system. This significantly distinguishes it from another similar structure - the rod one. It has a well-developed main root, capable of penetrating tens of meters deep into the soil. This is a characteristic feature of all plants of the Dicotyledonous class. But a fibrous root system also has advantages. For example, it can occupy a significant area, which increases the suction surface. In wheat, the fibrous root system occupies up to 126 cm in diameter with a length of up to 120. The degree of development of this structure completely depends on environmental conditions. In loose soil, corn's adventitious roots can grow within a radius of 2 m; in apple trees, up to 15 or more. At the same time, the depth of penetration is quite significant. In some weeds it reaches 6 m. That is why it is so difficult to get rid of them. If the soil is dense and the oxygen content in it is insufficient, then almost all adventitious roots are located in its surface layer.

So, the fibrous root system has a number of characteristic features. It is characteristic of plants of the Monocot class: the Cereal, Allium and Liliaceae families. This structure consists of which grow from the shoot in a bunch, occupying a significant area.