The meaning of cereals. What is zhito? The role of cereals in human life The importance of cereals in nature
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Presentation on the topic: Cereals
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Cereals Cereals (lat. Gramineae), or aphids (lat. Poáceae) - a family of monocotyledonous plants, which includes such well-known and long-used plants in agriculture as wheat, rye, oats, rice, corn, barley, millet, bamboo , sugar cane. Cereals are naturally distributed across all continents (one species is found even in Antarctica). They make up a significant part of the phytomass in many biocenoses, and in the steppes and savannas - the overwhelming majority.
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Cereal family (Poaceae, Gramineae). Grasses play an outstanding role in human life and occupy a dominant position in the formation of a number of types of herbaceous vegetation - meadows, steppes, prairies and pampas, as well as savannas. Approximately 900 genera and up to 11,000 species of cereals are known. In the CIS countries, over 1,500 species of cereals belonging to 198 genera naturally grow and are cultivated. The appearance of cereals is quite characteristic and they are recognized without much difficulty.
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Botanical characteristics As a rule, cereals are perennial herbs of dry treeless areas. Based on the type of root system, they are divided into three forms: rhizomatous (wheatgrass), loose-bush (red fescue) and dense-turf (fescue). The shoots are annual, erect, unbranched, ending in an inflorescence. There is no mechanism for secondary thickening of the stem. Branching occurs in the tillering zone or in the inflorescence area. The leaves are alternate, two-rowed, narrow, with an open sheath.
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General characteristics of the vegetative and generative organs of cereals. Cereals are a cosmopolitan family, equally well represented both in the tropics and in temperate and cold climates. All species of the family are not capable of secondary growth due to the absence of a cambium, but in representatives of the bamboo subfamily (Bambuсoideae), powerful stems become woody, reaching 25-30 m in tropical species. Among the grasses, there are many annuals, but perennial rhizomatous species predominate. Branching is often concentrated near the base, where the so-called tillering zone is located. The characteristics of branching in the tillering zone determine the life form of a particular cereal. The stem of almost all members of the family is thatch. It is made at the nodes and is most often hollow between the nodes.
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The leaves of cereals are alternate, divided into an open or closed leaf sheath covering the stem and a linear, subulate or lanceolate blade with parallel venation. At the base of the leaf blade there is often a membranous growth called a ligule or ligule. On the rhizomes, the leaves are modified and are more or less leathery scales. The sheaths serve as protection for the internodes, which retain the ability for intercalary or intercalary growth for quite a long time. The dead moisture of the lower leaves protects the base of the shoots from excessive evaporation or overheating. Ligula prevents the penetration of water, and with it pathogenic fungi and bacteria, into the vagina.
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Flowers of cereals are usually bisexual. Dioecious flowers are rare, for example in corn (Zea). They are collected in complex botryoid inflorescences of various types - panicles, racemes, cobs or ears. The basis of all these inflorescences are very characteristic of the entire family of elementary inflorescences - spikelets (Fig. 1). Each spikelet can contain from one to many flowers. A typical multiflowered spikelet consists of an axis, near the base of which there are two scales that do not bear flowers in the axils. These are the so-called upper and lower glumes. Often at the tops they end in bristly outgrowths - awns. Glumes are modified leaves, and their expanded part corresponds to leaf sheaths, and the spine corresponds to leaf blades.
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Flowers are located on the axis above the glumes. Their number has an important systematic significance. Each flower sits on its own short axis, which in relation to the axis of the spikelet can be considered a second order axis. The axes of the flowers emerge from the axils of the lower floral scales. Above the base of the lower lemma on the opposite side of the flower axis is the upper lemma. It often has two longitudinal keel ribs and a more or less noticeable notch at the top. Glumes are also considered modified leaves.
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Above the upper floral scale, on the axis of the flower, there are two small colorless scales called lodicules. It is believed that these are the remains of perianth. Most cereals have 3 free stamens, but some groups (rice - Oryza and bamboos - Bambusa) have 6 stamens. There are cereals with 8 (12) stamens. There is no consensus regarding the structure of the gynoecium. It is generally accepted that it is based on 3 fused carpels, forming a single-locular superior ovary with one ovule, i.e. the gynoecium in cereals is pseudomonocarpous. The style ends in two feathery stigmas. Sometimes, for example, in bamboos, stigmas are 3. Cereals are wind-pollinated plants. Cross pollination.
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The fruit of cereals is a pseudomonocarp: a caryopsis in which the membranous pericarp fits tightly to the seed and sometimes adheres to the spermoderm (seed coat). Rarely (in some tropical bamboos) the caryopsis has a succulent or woody pericarp. Most of the single seed consists of endosperm. The embryo is relatively small.
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Classification and significance of the cereal family. Plants belonging to approximately 30 genera are of significant agricultural importance, which will be given a brief description. Corn (Zea mays) is an annual monoecious plant. Origin: Mexico. In recent centuries it has spread throughout the globe.
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Corn One of the largest herbaceous cereals, the stem reaches a height of 5 meters or more, the leaves are large, up to 12 cm wide; male flowers are collected in an apical inflorescence - a panicle consisting of spike-shaped branches (Fig. 3). The spikelets are located on the branches in pairs; one is pedunculated, the other is almost sessile. Each spikelet consists of 2 glumes, between which there are 2 male flowers; lemmas 2. Stamens, like the vast majority of cereals, 3.
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Female flowers are collected in axillary inflorescences - cobs. Each cob has a multilayer wrapper formed by leaf sheaths. Single-flowered female spikelets with membranous spikelet and floral scales are arranged in pairs along the spadix in parallel rows. Of two paired spikelets, one develops; the flower in the other spikelet remains sterile. The style is long, thread-like with a forked stigma. At the time of flowering, a bunch of columns protrude from the cob. The male flowers of this plant ripen several days earlier than the female ones, which is how cross-pollination is achieved through the wind. Corn is a feed, food and industrial crop. In terms of area occupied on the globe, it is second only to wheat. A huge amount of corn is grown to make silage. Corn stalks, leaves and cobs are rich in sugar and ensile well. Grain is used as livestock feed, as well as for the production of a variety of food products. The chemical industry produces a range of synthetic products from corn stalks and corn cobs. Dry corn leaves and stalks are also used to make paper. Flower columns are harvested as medicinal raw materials (choleretic agent). There are several varieties of corn and hundreds of varieties. Corn hybrids have high yields.
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Sorghum (Sorghum) - 8 species grow in the CIS, only one of which is a perennial plant. All annual species are cultivated. These are large plants with paniculate inflorescences. Sweet sorghum (S. caccharatum) - cultivated in Ukraine, the North Caucasus and the Lower Volga region. Reaches a height of over 2 m. The stem is filled with parenchyma rich in sugar. Used for hay, green fodder, pasture and silage. Sometimes, under conditions that impair growth, young leaves accumulate hydrocyanic acid, causing poisoning in animals. The grain is also used to feed livestock.
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Drought resistant. The sorghum-humate hybrid is of great economic importance - a perennial forage plant obtained by crossing sorghum with a perennial rhizomatous weed - humate (S. halepense). Recommended for cultivation on sandy lands in arid zones. Drooping sorghum, or dzhugara (S. setit), is cultivated in Central Asia as a grain crop. The grain is used as food and as a concentrated feed.
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The Poaceae family is a large family of monocots, including about 10,000 species. Cereals are evenly distributed throughout the globe, forming grass cover. One species is even found in Antarctica. These are mainly annual and perennial herbs. Shrub and tree forms (bamboo) are rare. This family includes the most important cultivated cereals - wheat, rye, rice, oats, corn, barley, millet, as well as many wild cereals - timothy, bluegrass, foxtail, etc.
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In addition, cereals include various types of reeds and bamboo.
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All types of cereals have a fibrous root system. The stem is a straw, hollow at the internodes and filled with tissue at the nodes. At the base of the internodes there is educational tissue, due to which the stem grows in length. This type of stem growth is called intercalary. The leaves of cereals are narrow, simple, and consist of a long leaf blade and a sheath that clasps the stem at the nodes. The leaf venation is parallel. Cereals branch by tillering, that is, they form new shoots in the lower part of the stem, close to the ground. A cereal flower consists of two flower scales - outer and inner, which replace the perianth, three stamens with large anthers on long filaments, and one pistil with two stigmas. One of the flower scales is sometimes elongated in the form of an awn.
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The structure of a cereal flower
Flower formula O2+2T3P1
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The flowers of cereals are collected in inflorescences - spikelets, of which complex inflorescences are made - a complex spike (rye, wheat, barley), panicle (millet), cob (corn), plume (timothy) Spikelets consist of two spikelet scales covering one or more flowers.
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Cereals are pollinated by the wind, some (wheat) are self-pollinating. The fruit is a grain. Cereals reproduce not only by seeds, they also have vegetative propagation by shoots and rhizomes.
Lesson type - combined
Methods: partially search, problem presentation, reproductive, explanatory and illustrative.
Target:
Students’ awareness of the significance of all the issues discussed, the ability to build their relationships with nature and society based on respect for life, for all living things as a unique and invaluable part of the biosphere;
Tasks:
Educational: show the multiplicity of factors acting on organisms in nature, the relativity of the concept of “harmful and beneficial factors”, the diversity of life on planet Earth and options for adaptation of living beings to the entire range of environmental conditions.
Educational: develop communication skills, the ability to independently obtain knowledge and stimulate one’s cognitive activity; ability to analyze information, highlight the main thing in the material being studied.
Educational:
Formation of an ecological culture based on recognition of the value of life in all its manifestations and the need for a responsible, careful attitude towards the environment.
Forming an understanding of the value of a healthy and safe lifestyle
Personal:
nurturing Russian civic identity: patriotism, love and respect for the Fatherland, a sense of pride in one’s Motherland;
Formation of a responsible attitude towards learning;
3) Formation of a holistic worldview that corresponds to the modern level of development of science and social practice.
Cognitive: ability to work with various sources of information, transform it from one form to another, compare and analyze information, draw conclusions, prepare messages and presentations.
Regulatory: the ability to organize independent completion of tasks, evaluate the correctness of work, and reflect on one’s activities.
Communicative: Formation of communicative competence in communication and cooperation with peers, seniors and juniors in the process of educational, socially useful, educational and research, creative and other types of activities.
Planned results
Subject: know the concepts of “habitat”, “ecology”, “ecological factors”, their influence on living organisms, “connections between living and non-living things”;. Be able to define the concept of “biotic factors”; characterize biotic factors, give examples.
Personal: make judgments, search and select information; analyze connections, compare, find an answer to a problematic question
Metasubject:.
The ability to independently plan ways to achieve goals, including alternative ones, to consciously choose the most effective ways to solve educational and cognitive problems.
Formation of semantic reading skills.
Form of organization of educational activities - individual, group
Teaching methods: visual-illustrative, explanatory-illustrative, partially search-based, independent work with additional literature and a textbook, with COR.
Techniques: analysis, synthesis, inference, translation of information from one type to another, generalization.
The economic importance of cereals is very great. Almost all grain plants belong to this family.
Independent work of students with the textbook
Using the text of the textbook (textbook by I.N. Ponomareva § 45; textbook by V.V. Pasechnik § 53), write down all the main plants of the cereal family used in human life and economic activity, and indicate the area of their use
(About 5 minutes are allotted to complete the task, after which the students take turns naming one of the plants of this family, giving its brief description and indicating its areas of application. After completing this task, you can listen to the reports of some students.)
Oral presentations by schoolchildren
(Several students prepare mini-reports in advance for 2-3 minutes about one of the most interesting representatives of the cereal family. The remaining students draw up the information received in the form of a brief summary or a small table.)
Plants of the grass family
| Plant | Characteristics of the plant and its areas of application |
| Wheat | About 20 species and a large number of varieties are known; in Russia there are about 10 species. Hard and soft varieties are common. Used in baking, as well as for the production of semolina, pasta, and edible alcohol |
| Barley | There are 26 species (of which 8 are in Russia), as well as a large number of varieties. It is found wild in the southern regions of the country. Mainly two types are cultivated: two-row barley and common barley. Used in brewing, for the production of pearl barley and barley, and also as a fodder plant |
| Rye | About 8 species are known, in the flora of Russia 4. Distributed and cultivated mainly in temperate regions and semi-mountainous regions of the Northern Hemisphere. Rye is mainly grown as a spring (annual) and winter (biennial) crop. Used in baking for the production of black bread, for the production of edible alcohol |
| Oats | About 30 species, in Russia - about 15. Distributed mainly in Mediterranean countries. The inflorescence is complex. Simple spikelets are collected into a spreading panicle. Oats are cultivated as a valuable food (cereal) and fodder crop. |
| Millet | About 400 species are known, only 4 in Russia. It grows mainly in tropical and subtropical zones. Has a panicle inflorescence. Unlike many cereals, its stems not only bush, but also branch. Drought-resistant, non-frost-resistant plant. Millet is cultivated as a cereal plant, from which cereals (millet) and flour are obtained. Straw is used as feed and bedding for livestock, and is also used for the production of lower grades of paper. |
| Corn
| One species, divided into 8 subspecies. Not found in the wild. Flowers of different sexes. Male flowers are collected in an inflorescence panicle at the top of the stem, female flowers in an inflorescence spadix in the leaf axils. Monoecious plant. Stems can reach a height of 2-3 m. Cultivated in southern and warm temperate latitudes on all continents. They are grown to produce grain and flour (in some countries it is used to make bread). It is used as a fodder plant, as well as for the production of starch, alcohol, fiber, and paper. In addition, it is an oilseed crop, used in medicine as a diuretic and choleretic agent (columns with stigmas) |
| Rice | There are 24 species and about 2000 varieties. In Russia there are only 2 species. Distributed in tropical and sub-tropical countries. Hydrophytic plant. The spikelets are collected in paniculate inflorescences. Mainly two types are cultivated, the most important being rice. It is consumed as food, used as a raw material for the preparation of starch, alcohol, etc. Rice straw is used for making paper, as well as in applied arts |
| Sorghum | About 40 species are known, in Russia 3 (cultivated and weeds). Drought-resistant plant. Distributed in tropical countries, mainly in Africa. Common sorghum is a plant up to 6 m high. It is cultivated as a grain, fodder and industrial crop. Grain is processed into starch, sugar, alcohol |
| Sugar cane | 15 species are known; they are not cultivated in Russia (in the former USSR - in the south of Tajikistan). Distributed in the tropics and subtropics of both hemispheres. The stems contain up to 15-20% sugar. Used to produce sugar, rum, alcohol, molasses |
Continuation of the teacher's story with elements of conversation
In addition to the listed plants, the cereal family includes many cultivated food plants that are important in human life and economic activity. Let's list
just a few of them: French reigrass (a relative of oats), mogar, boron (Italian millet), gomi, chumiza, paidza (related to millet), as well as dzhugara (in Central Asia it is cultivated as a grain, fodder and industrial crop).
In addition to cultivated plants used by humans, many cereals are also environment-forming species (edificator species) in plant communities of meadows, steppes and forest-steppes. (Some representatives of wild plants of the cereal family can also be introduced using the material presented in schoolchildren’s reports.)
Tsitsaniyu broadleaf and water tsitsaniya (Canadian rice) are bred in lakes and reservoirs as a protective and food plant for waterfowl.
Different kinds feather grass are often the main ones in the vegetation cover of steppes. Many of them are valuable forage plants (Lessing's feather grass), and some can cause serious injuries and even death of livestock (feather grass, or tyrsa), and spoil the fur of animals.
Canary grass found in the middle zone and in the south of Russia in the wild. It is bred as a food plant for many species of indoor birds (“canary seed”).
Most common growing wild plants of the grass family are meadow timothy, meadow foxtail, meadow grass (turfgrass), cocksfoot, meadow bluegrass, meadow fescue, awnless brome, chicken millet, green bristle grass. Almost all of them are specially grown as valuable feed plants.
A relative of oats is the wild oat weed, which not only clogs the grain, but also dries out the soil. Wheatgrass is a difficult to eradicate weed (but the roots of wheatgrass are used in medicine), as well as Aleppo sorghum (Johnson grass), chicken millet, etc.
Stems of plants such as cane ordinary, reed grass ground, used as fuel, raw material for paper production, mats are woven from them, mattresses are stuffed with them, and also used for buildings (to cover roofs).
Some plants of the family, such as imperata cylindrical, large shaker, are grown in decorative purposes (mainly for dry bouquets). White tolevka and some bluegrass are used to decorate lawns.
The Russian biologist made a great contribution to the formation of modern ideas about the origin of cultivated plants N.I. Vavilov. He substantiated the theory about centers of origin cultivated plants, according to which the greatest diversity of natural forms (species and genera) is located in the centers of their origin. N.I. Vavilov identified 5 main centers of origin of cultivated plants.
Frontal survey
Answer the questions.
What family name is similar to the name “cereals”?
What signs are characteristic of plants of the grass family?
What life forms are represented by plants of this family?
Name a plant of the grass family that has a woody trunk.
Which plants of this family are used by humans as food?
List the wild forage plants of the grass family.
Why are there no honey plants among the plants of this family?
Give examples of plants from the grass family that are medicinal.
What parts of these plants are used medicinally?
What is the name of the fruit of cereals?
What is its difference from other dry single-seeded fruits?
What inflorescences are characteristic of plants of the grass family?
What is the stem of cereals called, what are its main features?
What methods of pollination are typical for plants of this family?
What is the difference between the concepts “species” and “variety”?
What type of root system is typical for plants of the grass family?
Creative tasks.
Determine which plants of the cereal family are used to make semolina, oatmeal, millet, pearl barley, and barley, from which flour, pasta, and oatmeal cookies are baked? What other cereal seeds are used for food? What other plants of the grass family do people use for food? What cereals are made from plants of other families?
Collect a collection of different rice seeds available in your area (usually at least 5 types). Measure and describe each of the samples. Indicate its color, shape, transparency and other characteristic features. Find information on the packaging about the growing area of this rice variety.
Assignments for students interested in biology.
Collect information about N.I.’s research. Vavilova. Find out from which regions of the globe various types of cereals cultivated by humans originated. Map the centers of origin of different types of cereals
Prepare a report on interesting families of the monocot class that were not covered in class.
Department of angiosperms. Family of cereals. Diversity of plants of the grass family
Food plants. General characteristics of cultivated plant families.
Food plants. Cereals. Wheat, rye, barley, oats, corn, rice, millet, etc. Part 1
FamilyCereals(Bluegrass). Theory and practice of the Unified State Exam/OGE 2017. Biology.
Resources:
I.N. Ponomareva, O.A. Kornilov, V.S. Kuchmenko Biology: 6th grade: textbook for students of general education institutions
Serebryakova T.I.., Elenevsky A. G., Gulenkova M. A. et al. Biology. Plants, Bacteria, Fungi, Lichens. Trial textbook for grades 6-7 of secondary school
N.V. Preobrazhenskaya Biology workbook for the textbook by V. Pasechnik “Biology 6th grade. Bacteria, fungi, plants"
V.V. Pasechnik. Manual for teachers of general education institutions Biology lessons. 5-6 grades
Kalinina A.A. Lesson developments in biology grade 6
Vakhrushev A.A., Rodygina O.A., Lovyagin S.N. Verification and control work for
textbook "Biology", 6th grade
Presentation hosting
The importance of cereals in human life is so great and varied that it deserves special consideration. In the first place should be placed grain and cereal crops, of which wheat, rice and corn are rightly considered the main food plants of mankind. In terms of the area occupied by their crops - according to 1980 data, about 225 million hectares - wheat ranks first among all cultivated plants. Although it is primarily an extratropical crop, the development of a number of new varieties (especially Mexican varieties) has significantly expanded the crop's acreage within the tropics.
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The number of wheat species (Fig. 215) in their narrowest scope reaches 20-27, a significant majority of which are known only in cultivation. The most ancient and, apparently, ancestral for all other types of wheat are wild diploid (with 2n = 14) einkorn wheat: Boeotian (Triticum boeoticum) and Urartu (T. urartu), widespread in South-West Asia (including in Southern Transcaucasia), in Crimea and on the Balkan Peninsula and having ears that easily disintegrate into single-spike segments. In addition, the grains of these wheats are tightly enclosed in flower scales and are threshed from them with great difficulty. In the process of domestication of Boeotian wheat, einkorn wheat (T. monococcum) was formed, which differs from it in its non-disintegrating ears, but still retains poorly threshed, so-called membranous grains with a small number of them in the ear (1, rarely 2). It was the grains of this wheat with a small admixture of grains of its ancestor - Boeotian wheat - that were found during archaeological excavations in Iran and Turkey dating back to the 65th-54th centuries. BC e. It is assumed that significantly more productive tetraploid (with 2n = 28) and hexaploid (with 2n = 42) wheat arose not only as a result of the continued cultivation of einkorn wheat by ancient farmers, but also as a result of their hybridization with diploid species of the closely related genus Aegilops ( Fig. 215, 10). At the same time, tetraploid wheats were first formed, which are divided into a group of emmer, or emmer, and a group of durum wheats, which received their name because of the glassy consistency of the protein-rich endosperm of the grains. Among the emmers there are also wild species with disintegrating ears: double grain wheat (T. dicoccoides) and Ararat wheat (T. araraticum). The once widely cultivated emmer wheat (T. dicoccon) is now only occasionally sown as a cereal crop and in experimental plots. Durum wheat includes only cultivated species: durum wheat (T. durum), from the grains of which protein-rich flour is obtained, which is used for the preparation of high-quality pasta; fat wheat (T. turgidum), some varieties of which have branched ears (the so-called branched wheat) , and other, much less commonly cultivated species. If spelts still have filmy grains, then durum wheat already belongs to the group of hulless wheats with easily threshed grains.
The “youngest” hexaploid wheats are represented exclusively by cultivated species, of which spelled wheat (T. spelta) and macha wheat (T. macha) are the oldest and still preserved filmy grains. Like spelled, they are currently cultivated mainly in experimental plots. Finally, naked hexaploid soft or summer wheat (T. aestivum), which is a kind of pinnacle of wheat evolution, is the most productive and is cultivated almost throughout the globe. It is currently represented by more than 400 cultivated varieties, the number of which is increasing due to the ongoing selection of this wonderful crop in almost all countries. It should be noted that in the experimental plots of the All-Union Institute of Plant Growing (Leningrad) there is a rich living collection of species and varieties of wheat, begun on the initiative and with the participation of the outstanding Soviet biologist N.I. Vavilov.
Like wheat, the most important grain and cereal crops such as rye, barley and oats originate from the Mediterranean countries, although they have retained closer ties with their wild relatives than cultivated wheat. Rye (Secale cereale, Fig. 213) has been known in cultivation since the end of the Bronze Age, and currently occupies relatively large areas in Eurasia, North and South Africa, North America, southern South America and Australia. It is believed that rye was introduced into the culture by humans due to a kind of natural selection. When the wheat crop moved north and to higher mountainous areas, it often died and was replaced by the more cold-resistant rye (S. segetale), which had previously been a weed in wheat crops. In such cases, farmers were forced to collect grains of brittle-eared weedy field rye, from which later, through unconscious selection, rye with non-disintegrating ears was formed. In addition to the two rye species mentioned, several closely related perennial species, often collectively called mountain rye (S. montanum), are found in the mountainous regions of the Mediterranean and Western Asia, including the Caucasus. It is worth noting that recently stable hybrids between rye and wheat - triticale (Triticale) have been obtained, which open up new opportunities for the selection of these crops. Cultivated common barley (Hordeum vulgare, Fig. 213, 6-11) and two-row barley (H. distichon) are not only food plants (providing pearl barley and barley grains, flour, as well as raw materials for the brewing industry), but also the most important forage plants . The closest ancestor and probable ancestor of both cultivated barleys - wild barley (H. spontaneum) with ears that fall apart during fruiting, is distributed on the rocky and fine-earth slopes of the countries of the Eastern Mediterranean and Western Asia, and is often found there as a weed in crops of cultivated barley. In archaeological finds of barley of the oldest age (about 7000 BC) in the territories of Jordan and Iran, only grains of wild barley are found. Later, forms with partially disintegrating ears begin to appear, and then the grains of two-row barley that arose in the culture. Common or multi-row barley (all 3 spikelets in groups of 3 spikelets are sessile and fully developed), which is the most valuable economically, apparently originated from two-row barley by mutation in conditions of a relatively more humid climate. Currently, over 200 varieties of cultivated barley are known, the main areas under cultivation of which are in Eurasia, North Africa, North America and Argentina, and in Tibet barley is cultivated to altitudes of 4600 m.
The economic use of cultivated types of oats, of which the most important is oats (Avena sativa), is in many ways similar to barley. In addition to such valuable dietary products as oatmeal, oat flakes and oatmeal, oats provide the best concentrated food for pets. In addition, like barley, it is often sown in a mixture with or without legumes to obtain green mass that is very valuable for fodder. Of approximately 25 wild oat species, wild oat (A. fatua) is the closest to oat and, apparently, is its ancestor - a common weed in oat crops. It is distinguished by the axis of the spikelets, which easily disintegrates into segments at the joints, and by much more developed, geniculately bent awns (Fig. 212, 1-4). It is likely that, like rye, oats entered the culture, having first been a weed in the crops of the oldest cultivated types of wheat. Currently, oats are widely cultivated in Eurasia (in the north up to 69.5° N) and North America.
Rice (Oryza sativa, Fig. 196, 1-5) is the most important food plant in tropical and subtropical countries. How great its importance can be judged by the fact that it serves as the main food for about 60% of the total population of the Earth. The areas occupied by this crop are especially large in East, Southeast and South Asia, which is probably the homeland of rice, since it has been known here since the Stone Age. The oldest written sources of China mention that already in 2800 BC. e. rice was widely cultivated and was one of the 5 sacred plants, which also included millet, wheat, barley and soybeans. The ancestors of rice were probably species of this genus with spikelets falling off at the joints during fruiting, for example, wild rice (O. rufipogon) - a malicious weed of cultivated rice crops. Rice provides cereals and flour, as well as raw materials for the production of starch, beer, rice oil and other products. Rice straw is used for various crafts and paper production. Thanks to the development of new, early-ripening varieties, it became possible to expand the rice culture on the territory of the USSR. It began to be cultivated in the Kuban basin, in the Crimea, in the Volga delta, and in the south of the Far East.
Rice is a moisture-loving plant, as a result of which its fields must be periodically flooded with water. True, there are also so-called dry-land varieties, but they are much less productive.
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Another important food and feed crop for humanity is corn, or maize (Zea mays, Fig. 209). Corn is cultivated in almost all tropical, subtropical and warm temperate regions of both hemispheres, but the main areas of its cultivation are Central and South America, the USA, Southern and Southeast Europe, China, India and South Africa. Unlike all other cultivated grains, corn is of American origin. In the southwestern United States, Mexico, Central America, Peru and Chile, it has been known since ancient times, being one of the objects of worship (Fig. 216). Remains of cobs from caves in Mexico and surrounding countries have an age of 3400-5000 years, determined using the radiocarbon method. The ears of that time were small (often 5-7 cm long), the grains in them were also small and covered with well-developed flower scales (i.e., membranous). Obviously, corn has since gone through a long evolutionary path in the direction of increasing yield through unconscious and then conscious selection. Regarding the origin of corn, not everything is clear yet, but it is very likely that its immediate ancestor or one of the ancestors is a common weed plant in Mexico (often a weed of corn crops) Mexican teosinte (Euchlaena mexicana, Fig. 209, 4-5) which is similar in appearance to corn, but having in the axils of the upper stem leaves not cobs, but two-row ears with an axis splitting into segments. The genus Teosinte, which includes 4 species, 2 of which are perennials, is undoubtedly the closest relative of corn and often even joins this latter genus. In addition, corn and Mexican teosinte have the same number of chromosomes (2n = 20) and interbreed easily with each other. It is assumed that the evolution of maize could have been constantly promoted by introgressive hybridization of its primary forms with teosinte species, and possibly with species of another closely related genus Tripsacum (Tripsacum, Fig. 209, 7).
It is worth noting that only very recently, in a remote mountainous region of Mexico, an American-Mexican expedition discovered a second perennial species of teosinte, called “diploid perennial corn” (Zea diploperennis; its author, X. Iltis, combines the genus teosinte with corn ). This species, in contrast to the previously known perennial teosinte - Euchlaena (or Zea) perennis - with 2n = 40, like cultivated corn, has a diploid number of chromosomes - 2n = 20. Thus, this find opens up the possibility of successful crossing of corn with its perennial relative in order to create perennial cultivated corn, as well as to give corn other useful properties, in particular greater cold resistance, since diploid perennial corn can grow at altitudes up to 3000 m. The economic use of corn is very diverse. Flour and cereals are obtained from its grains, and not fully mature grains and whole cobs are eaten directly, boiled or canned. In addition, corn starch is obtained from grains - a valuable raw material for the production of alcohol, glucose and other products, as well as corn oil. Corn cobs and green mass, both fresh and ensiled, are the best food for domestic animals. Based on the structure and consistency of the grains, numerous varieties and varieties of corn are divided into a number of groups that have different uses: flint, tooth-like, starchy, sugar, waxy, etc. A small-fruited group of varieties, the so-called “popping” corn, is used to obtain a special delicacy called “ snow flakes." Particularly high corn yields are obtained when sowing seeds of intervarietal and interline hybrids.
Cereals also include a number of crops that are of great nutritional and feed importance. In the USSR, the most famous of them is millet (Panicum miliaceum), apparently originating from inland regions of Asia, where the weedy subspecies of this species with spikelets falling off at the joints with fruits is predominantly widespread - probably the direct ancestor of cultivated millet. Millet is used for food mainly in the form of cereals (millet), which is also an excellent concentrated feed. In South Asia, another species is used for the same purposes - Sumatran millet (P. sumatrense). Cereals suitable for human nutrition and valuable concentrated feed are also provided by many types of sorghum (Sorghum), the culture of which is especially widespread in Africa, South and East Asia, mogar, or chumiza (Setaria italica), pearl millet (Pennisetum americanum), caracan, or dagussa (Eleusine caracana), tef (Eragrostis tef), some species of barnacle (Echinochloa), crabgrass (Digitaria) and buckwheat (Paspalum), already mentioned above in a brief overview of the tribes. Apparently, the grains of many other cereals are also suitable for food, from which new economically valuable crops can be obtained through selection.
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Of the cereals in which not the grains, but other parts of the plant are eaten, the first place is undoubtedly occupied by sugar cane (Saccharum officinarum, Fig. 210, 1, 2, Table 45, 1), which produces more than half of the world's sugar production. The homeland of cultivated sugar cane has not been precisely established, but it is most likely that it was first introduced into cultivation in India. In Europe, they learned about sugar cane only after the campaign of Alexander the Great in India. In Asia (including Central Asia), the most common wild relative of sugar cane is wild sugar cane, or kalam (S. spontaneum), which is probably its ancestor. In East, Southeast and South Asia, young shoots of many types of bamboos are of significant nutritional value. Thus, one of the trading posts on the island of Taiwan receives about 150 tons of shoots every day. Young shoots of zizania, reed and some other cereals are also used as a vegetable.
In second place in importance is the use of cereals as feed plants for domestic animals. It has already been noted that many food grains, especially corn, oats and barley, provide excellent concentrated feed and high-quality green mass. In addition, cereals are the main components of natural hayfields and pastures, especially meadows and steppes of various types. The best wild species in terms of their feeding qualities have not only been introduced into cultivation, but are also represented by a number of cultivar varieties. Particularly widely cultivated are meadow timothy grass, hedgehog grass, meadow fescue and tall fescue, awnless brome, perennial and many-flowered tares, meadow foxtail, giant bentgrass, meadow bluegrass, tall ryegrass, and in forest-steppe and steppe regions - comb, desert and brittle wheatgrass. Among the forage cereals introduced into cultivation in tropical and subtropical countries, species from the millet, sorghum and pigwort tribes naturally predominate.
Many of the fodder grains listed above are also used in ornamental gardening as lawn plants. In the USSR, lawns made from the species of chaff, fescue, bentgrass, wheatgrass, ryegrass, and bluegrass are especially common. In subtropical parks, species that form dense mats are very good for creating lawns, such as the one-sided narrow furrow (Stenotaphrum secundatum) with blunt or even notched leaves at the top and thin-leaved zoysia (Zoysia tenuifolia) with very narrow bristly leaves. Large densely turfy species - pampas grass, Chinese miscanthus, shiny feather grass, pinnate feather grass, etc. - are planted in single plantings in parks, squares, gardens, and near roads. Large moisture-loving cereals - reed, manna, zizania, etc. - are suitable for planting along the banks of reservoirs. Many of the ornamental grasses have variegated varieties (usually leaves with white longitudinal stripes), of which in the USSR the meadow grass variety Phalaroides arundinacea is especially often cultivated, the shoots of which are added to bouquets. Especially for the preparation of dry bouquets, maned barley (Hordeum jubatum) with drooping long-spined ears, ovoid haretail (Lagurus ovatus) with hairy ellipsoidal or ovoid spike-shaped panicles, golden lamarckia (Lamarckia aurea) with one-sided golden heads are cultivated. fir trees, large shaker (Briza maxima) with large , slightly swollen spikelets in a panicle and some other species. Some wild grasses with beautiful panicles are also suitable for bouquets, for example, species of shaker and bison, Lerchenfeldia flexuosa, etc. For the manufacture of beads and other jewelry in South and Southeast Asia, common beadweed (Coix lacryma-jobi, rice) is widely cultivated 210, 7-9). Beads made from its false fruits are found during excavations in Central Asia.
In gardens and parks of tropical and subtropical regions, as well as in greenhouses, bamboo culture is very common. In the USSR, on the Black Sea coast of the Caucasus and Crimea, the most frequently cultivated species are phyllostachys, pseudosaza japonica, bluish bamboo, and multibranch species.
Cereals are also used to stabilize shifting sands, various kinds of embankments, and mine dumps. On the coastal dunes of Northern Europe, long-rhizomatous species are usually planted for these purposes - Ammophila arenaria and Leymus arenarius, and in the sandy deserts of Central Asia - L. racemosus and seline species. For securing embankments and mine dumps, the most “active” and unpretentious grasses with long rhizomes are suitable, especially creeping wheatgrass, awnless brome, ground reed grass, and in subtropical areas - palmate.
Only a few types of cereals contain aromatic substances used in perfumery, food industry and medicine. In the USSR, the most famous species containing coumarin are bison (Hierochloe) and fragrant spikelet (Anthoxanthum), used to add flavor to various drinks. Essential oils used in perfumery and medicine (as an antiseptic) are obtained from the species of Vetiveria zizanioides, Cymbopogon citratus and C. nardus, widely cultivated in the tropics. If in vetiver the essential oil - vetiverol - is contained mainly in the roots, then in the shuttlebeard species the essential oil with a strong citrus odor is contained mainly in the leaves and scales of the spikelets. All 3 species were originally introduced into cultivation in South and Southeast Asia (India, Burma, Sri Lanka, Malaysia), and lemon beetle is not known in the wild. The stigmatic branches of corn, the rhizomes of wheatgrass and some other cereals are also used as medicines.
The technical uses of cereals are very diverse. Durable and lightweight bamboo stems are widely used as a building material and for various crafts in tropical and subtropical countries. They are often even used as water pipes and other pipes. In the USSR, in Western Transcaucasia, there are also small plantations of the plant, the stems of which are used mainly for the manufacture of ski poles and fishing rods. In extratropical countries, reed stems are used as building material for small buildings, both directly and in the form of a compressed mass called “reed.” Reed stems are also suitable for various crafts, in particular as a material for weaving. In addition, the fast-growing stems of bamboo, reeds and some other large grasses, growing in large clumps, are excellent raw materials for paper production, replacing the more valuable wood of slow-growing trees. Paper of particularly high quality is produced from the stems of the Western Mediterranean esparto feather grass (Stipa tenacissima), the fibers of which are also used to make ropes, ropes and coarse fabrics, and more recently also rayon. Similar applications can be found in other large cereals with very tough stems and leaves, for example, shiny cherry, Ravenna woolflower (Erianthus ravennae), cylindrical imperata, etc. Some varieties of sweet sorghum (Sorghum saccharatum) with fan-shaped panicles, sometimes distinguished as a special type of technical sorghum (S. technicum), are widely cultivated in many countries, including the USSR for the production of brooms. The very strong roots of some grasses, especially the Central American Epicampes macroura and the Mediterranean Chrysopogon gryllus, are used to make brushes.
Cereals also have some negative significance in human life, although, of course, it is completely incommensurate with the benefits they bring. Among cereals, there are many weeds in crops and plantations of various crops, causing significant damage to them. In extratropical countries, the most common field weeds include creeping wheatgrass, rye brome, wild oats, broom (Apera spica-venti), bristle grass species, millet grass (Echinochloa crus-galli), and annual bluegrass. Rice crops are often seriously damaged by specialized weeds such as rice grass (Echinochloa oryzoides) and hairy woolgrass (Eriochloa villosa). In fields and plantations of tropical and subtropical regions, the number of cereal weeds increases significantly. The most famous of them include Aleppo sorghum, or gumai, imperata alang-alang, pigweed, double buckwheat, Indian elefsina (Eleusine indica), many species of bristle grass, barnyard grass and millet. Some damage to forestry is caused by ground reed grass and reed grass growing in forest clearings. The “weeds” of our northern meadows are considered to be the species of low value for food: the soddy pike (Deschampsia caespitosa) and the white beetle.
Life of plants: in 6 volumes. - M.: Enlightenment. Edited by A. L. Takhtadzhyan, editor-in-chief, corresponding member. USSR Academy of Sciences, prof. A.A. Fedorov. 1974 .
You will learn from this article what the importance of the cereal family is in nature and human life.
The meaning of cereals
Cereals are perennial (less commonly, annual or biennial plants). Underground shoots sometimes change into rhizomes. For example, in bamboo the stem becomes woody. Most cereals are characterized by the structure of a stem that is hollow at the internodes—thatch. Sugarcane and corn have loose stems with storage tissue. Almost every stem is characterized by intercalary growth. In cereals, the leaves are sessile, elongated, simple, alternately arranged, with parallel veins. The root system is fibrous.
The importance of cereals in human life
Representatives of cereals are excellent forage grasses. They play an important role in pasture and hayfields. Meadow fescue, creeping wheatgrass, and awnless brome are especially valued. There are also grains that animals do not like to eat - whitefish and pike. The economic importance of cereals for humans is determined by their nutritional value. They are considered important food and grain crops. The most important of them are rice, corn and wheat. Pasta, bread products, and cereals are made from their grains. In tropical countries, sugar cane is grown, the elongated stems of which contain up to 20% sugar. In subtropical and tropical countries, bamboo is grown and used as a building material. It is used to make decorative items and furniture. High-quality oil is produced from corn grains. Rice grains are not only consumed as food due to the presence of starch in their composition, but also refined varieties of powder are produced from them. Rice straws are used to make hats, baskets, the best types of paper, and furniture. Many cereals are ornamental plants.
The importance of cereals in nature
Cereals are specially grown in gullies and ravines to consolidate sand and prevent soil collapse. With their roots they loosen and enrich the soil. Grains also play a negative role: among them there are weeds - bristle grass, wild oats, wheatgrass. They have a well-developed rhizome and reproduce vegetatively. Therefore, crops of cultivated plants can be drowned out in the shortest possible time.
