Monocots appeared on planet Earth almost at the same time as dicotyledons: more than a hundred million years have passed since then. But botanists have no consensus on how this happened.
Supporters of one position argue that monocots evolved from the simplest dicotyledons. They developed in damp places: in reservoirs, on the banks of lakes and rivers. And defenders of the second point of view believe that monocots originate from the most primitive representatives of their own class. That is, it turns out that the forms preceding modern colors, could also be herbaceous.
Palmaceae, grasses and sedges - these three families took shape and spread towards the end. But bromeliads and orchids are perhaps the youngest.
Monocots belong to the class Angiosperms, the second largest. They number about 60,000 species, 2,800 genera, and 60 families. Of the total number, monocots make up a quarter. At the turn of the 20th-21st centuries, botanists expanded this class by splitting up several previously identified families. In this way, for example, lilies were distributed.
The orchid family turned out to be the most numerous, followed by cereals, sedges, and palms. And the smallest number of species is aroid - 2,500.
The generally accepted system of classification of monocot flowering plants, widely used throughout the world, was developed in 1981 by a botanist from the USA, Arthur Cronquist. He divided all monocots into five subclasses: commelinids, areciids, zingiberids, alismatids and liliids. And each of them also consists of several orders, the number of which varies.
Monocots belong to Monocotyledones. And in the classification system developed by APG, which names groups solely based on English language, they correspond to the Monocots class.
Monocots are represented mainly by herbs and, to a lesser extent, by trees, shrubs and vines.
Among them there are many that prefer marshy areas, ponds, and reproduce by bulbs. Representatives of this family are present on all continents of the globe.
Monocots received their Russian name based on the number of cotyledons. Although this method of determination is neither sufficiently reliable nor easily accessible.
It was the English biologist J. Ray who first proposed the distinction between monocots in the 18th century. He identified the following characteristics first class:
Stems: sparsely branched; their vascular bundles are closed; conducting bundles are placed randomly on the slice.
Leaves: mostly stem-covering, without stipules; usually narrow in shape; venation arcuate or parallel.
fibrous; adventitious roots very quickly replace the germinal root.
Cambium: absent, therefore the stem does not thicken.
Germ: monocotyledonous.
Flowers: perianth consists of two-, maximum - three-membered circles; the same number of stamens; three carpels.
However, individually, each of these characteristics cannot clearly distinguish between dicotyledonous and monocotyledonous plants. Only all of them, considered as a whole, make it possible to accurately establish the class.
Detailed solution paragraph § 16 in biology School 2100 for 6th grade students, authors S.N. Lovyagin, A.A. Vakhrushev, A.S. Rautian. 2015
- Gdz tests in Biology for grade 6 can be found
Question 1. Do you agree with the biologist's explanation? What other arguments can you give? Yes, I agree. It is very important to be able to distinguish and know certain plants. Even walking near some plants is dangerous - Sosnovsky's hogweed - when it comes into contact with the skin, a person gets a severe burn.
What problem could a dialogue between Antoshka and a biologist be a reason for discussing? Compare your version with the author’s (p. 141). By what characteristics and why are plant species distinguished?
Question 2. What is a species? (5th grade)
A species is a historically established set of populations, individuals of which are similar in morphological, physiological and biochemical characteristics, are adapted to certain living conditions and occupy a certain area in nature - a range, and are also capable of interbreeding with each other to form fertile offspring.
What is a sign? (Life experience)
A sign is an indicator, a sign, a sign by which one can recognize or determine something.
What shape are the leaf blades? (§ 11–12)
The shape of the leaf blade is determined by the ratio of length and width and by which part of the blade has its greatest width. There are round, oval and oblong; broadly ovate, ovate and lanceolate; obovate, obovate and oblanceolate. Linear. In addition to these ten basic forms, there are some non-standard types of leaves that do not fit into the above classification of leaf blades according to the ratio of length and width. Among woody plants, these are scaly leaves (thuja occidentalis), needle-shaped (spruce, pine, juniper), heart-shaped (linden), rhombic (euonymus warty) and triangular (bittersweet nightshade, currant).
According to the shape of the top of the plate, the leaf can be: obtuse (1), sharp (2), pointed (3), pointed (4), notched (5).
The base of the leaf blade is: wedge-shaped (6), rounded (7), heart-shaped (8), arrow-shaped (9), spear-shaped (10), unequal (11), cut (truncated) (12) and narrowed (13).
Based on the shape of the edge of the blade, leaves are distinguished: entire-edged (1); jagged, when both sides of the teeth are equal (2); serrated, when one side of the teeth is longer than the other (3); crenate - with rounded teeth (4); notched (5); wavy (6). If the teeth different sizes- leaves are distinguished between double-toothed (7) and double-serrate (8).
What is a cotyledon? (§ 5)
Cotyledons are the first leaves of the embryo, which can contain a supply of nutrients.
What forms of venation do you know? (§ 11–12)
Types of leaf venation: arcuate, parallel, reticulate (or pinnate), palmate.
What systematic groups do you know? (5th grade)
Similar species are grouped into genera, genera into families, families into orders (in animals, orders), orders into classes, classes into divisions (in animals, phyla), divisions into kingdoms.
Question 3. Choose the most convenient characteristic for distinguishing dicotyledons and monocotyledons.
One character is not enough to distinguish between dicotyledonous and monocotyledonous plants.
Conclusion: dicotyledons and monocotyledons flowering plants differ in a number of characteristics (in the table).
Question 4. My biological research
Verbal portrait of a dicotyledonous plant (description of the appearance of a dicotyledonous plant according to plan).
1. Erect stem.
Question 5. Tell us about the shape of these leaves.
Types of leaves: 1. The leaf is simple, deltoid. 2. The leaf is simple, whole-lobed. 3. A simple sheet, completely divided. 4. The leaf is complex, trifoliate. A complication can be seen in the division of the leaf blade.
Leaf outline: 5. The leaf is simple, lanceolate. 6. Elliptical or oval. 7. Ovoid. 8. Inversely cordate. 9. Heart-shaped.
Leaf blade edge: 10. Crenate-toothed. 11. Notched. 12. Serrated.
Stipule shape: written in the picture.
Venation: 17. Reticulated. 18. Parallel. 19. Arc-shaped. 20. Finger.
Question 6. Assignment. Describe the appearance of the plants shown below according to the plan. Write only about those features that are visible in the picture.
St. John's wort.
1. Erect stem.
2. Simple, solid sheet. Oblong-ovate or linear-oblong in shape. Its apex is sharp and its base is wedge-shaped. The leaf edge is entire. There are no stipules, the leaves are opposite and sessile.
3. Flower. The perianth is double, separate-petalled. The flower is correct. A corolla of 5 petals of golden yellow color. There are many stamens, they grow together in threads of three bundles. Calyx with five separate sepals. One pestle. The type of inflorescence is a wide panicle or almost corymbose inflorescences.
Medicine letter.
1. Upright shoot. 2. The transverse shape of the stem is round.
3. Leaves are entire, opposite. It is oblong-ovoid in shape, its apex is obtuse and its base is heart-shaped. The edge of the leaf is crenate. There are no stipules. The venation is pinnate.
4. The flower is irregular, bisexual. Double perianth. The corolla is fused-petalled, tubular. The calyx is single, whole, with 5 sepals. Stamens and pistils are not visible. The flowers are collected in a spike-shaped inflorescence.
Common blackhead.
1. Upright shoot.
2. Leaves are entire, opposite. Oblong-ovate in shape, the apex is obtuse and the base is wedge-shaped. Entirely edged or unclearly toothed. There are no stipules. The venation is pinnate.
3. The flower is wrong. Double perianth. The corolla is fused-petalled, tubular, two-lipped, longer than the calyx, with a straight tube. The calyx is two-lipped, with short sharp teeth. Stamens and pistils are not visible. The flowers are collected in apical, dense, spike-shaped inflorescences.
Great celandine.
1. Upright shoot. 2. The root is taproot, branched, with a short rhizome. The stems are branched.
3. Leaves are alternate, compound, dissected into crenate-lobed lobes. The leaf segments are ovoid or round, at the base with an additional lobe in the form of an eye, irregularly round-toothed, whole or notched on the underside. The venation is pinnate.
4. The flower is regular, double. The corolla is regular, consisting of 4 bright yellow, obovate petals. The calyx consists of 2 sepals. Stamens numerous, shorter than corolla. One pestle. Flowers are collected at the ends of the stem and branches in umbrella-shaped inflorescences.
A tenacious creeping creature.
1. Flowering stems are erect.
2. Leaves are simple. Spatulate (oval), with wavy, notched and short-toothed edges. The basal leaves are collected in rosettes. The leaves are in rosettes - with long petioles, the leaves on the stems are sessile; Bracts are ovate, entire, the lower ones are longer than the flowers, the upper ones are shorter. There are no stipules, the venation is pinnate.
3. The flower is irregular, the perianth is double. The flowers are two-lipped, located in the axils of the leaves, collected in whorls of 6-8 pieces. The corolla is fused-petalled, tubular. The calyx is pubescent, bell-shaped, with five triangular teeth. The stamens and pistil are not visible in the picture. Inflorescences are spike-shaped.
Yellow lily.
1. Upright shoot. 2. Leaves: entire, petiolate, ovoid in shape, with serrated edges. The venation is pinnate.
3. The flower is irregular, double. The corolla is fused-petalled, tubular, has an ovoid upper lip and a pointed, three-lobed lower one. The calyx is whole. Yellow flowers collected in false whorls at the ends of the shoots. 4 stamens, one pistil.
European swimsuit.
1. Shape of shoot (short, erect, recumbent, ascending, hanging, climbing, curly, fleshy).
3. Leaves are compound, palmately divided, sessile with a serrated leaf margin. The venation is palmate.
4. The flower is regular, double, single. The corolla is separate-petalled, with 10-20 sepals. There are many stamens and pistils.
Common sorrel.
1. Stemless plant. 2. Oxalis has a leaf similar to a clover leaf - trifoliate, but with a clear notch at the end of each of the three leaves. The leaf is complex and dissected. Each leaf blade is obversely cordate, the apex is notched and the base is wedge-shaped. The leaf edge is entire.
3. The flower is regular, double. The corolla is separate-petalled with five petals. The calyx is single with five separate sepals. Stamens 10. Pistil one.
The flowering plant division is divided into two classes: monocotyledons and dicotyledons. Differences:
- Monocots have one cotyledon (germ leaf) in the seed, while dicots have two.
- In monocots root system fibrous, and in dicotyledons it is rod-shaped.
- In monocots the leaf venation is parallel and arcuate, while in dicots it is reticulate (pinnate).
- Monocots do not have a cambium, so they cannot grow in thickness and are all herbs. Dicotyledons have a cambium, so they can be herbs, shrubs, and trees.
- The number of flower elements (stamens, petals) in monocots is a multiple of three (3,6,9...), and in dicotyledons - five (5, 10, 15...)
Monocots
- Family Cereals (rye, wheat, wheatgrass) - straw stem, intercalary growth, complex spike inflorescence, caryopsis fruit.
- The Liliaceae family (onion, tulip, lily of the valley) - have rhizomes and bulbs.
Dicotyledons
- Family Cruciferous (radish, cabbage, rapeseed) - 4 petals, fruit pod.
- Family Legumes, also known as Papillonaceae (peas, clover, beans) - bean fruit, nodule bacteria.
- Family Solanaceae (potatoes, tomatoes, peppers) - fused sepals and petals, poisonous.
- Family Asteraceae (sunflower, chamomile, dandelion) - small flowers collected in an inflorescence - a basket, a fruit - an achene.
- Rosaceae family (apple, strawberry, rowan).
Thus, the division of flowering plants into classes occurs on the basis of the structure of the root system, the number of cotyledons, leaf venation, etc. The division into families occurs on the basis of the structure of flowers and fruits.
1. Choose three correct answers out of six and write down the numbers under which they are indicated. Plants with leaf veining shown in the figure are also characterized by the following characteristics:
1) two cotyledons in the seed
2) the number of flower parts is a multiple of three
3) diffuse structure of the conducting system
4) the cambium ring is missing
5) tap root system
6) flower with double perianth
Answer
2. Select three characteristics that are characteristic of the organism shown in the figure.
1) vegetative propagation
2) parallel veining
3) double fertilization
4) four-membered flower
5) stem - straw
6) fruit – multi-nut
Answer
1. Choose three correct answers out of six and write down the numbers under which they are indicated. What characteristics are characteristic of plants of the family whose representative is shown in the picture?
1) fruit achene
2) straw stem
3) intercalary growth
4) compound leaves
5) reticulate venation of leaves
6) inflorescence complex spike
Answer
2. Choose three correct answers out of six and write down the numbers under which they are indicated. What signs are characteristic of this organism?
1) parallel veining of leaves
2) straw stem
3) the presence of cambium in the stem
4) fruit - achene
5) fibrous root system
6) vegetative propagation
Answer
Choose the one that suits you best correct option. In Asteraceae the fruit
1) grain
2) achene
3) drupe
4) nut
Answer
Choose three correct answers out of six and write down the numbers under which they are indicated. What characteristics are characteristic of plants of the Dicotyledonous class?
1) reticulate venation of leaves
2) the root system is fibrous
3) tap root system
4) arc venation of leaves
5) two cotyledons in the seed
6) parallel veining of leaves
Answer
1. Establish a correspondence between the classes of plants (1-Dicotyledons, 2-Monocotyledons) and their characteristics. Write numbers 1 and 2 in the correct order.
A) Fibrous root system
B) Tap root system
B) Leaves have arcuate or parallel veins
D) The number of flower parts is a multiple of 3
D) Leaves have pinnate or palmate veins
Answer
2. Establish a correspondence between the trait of angiosperms and the class for which it is characteristic: 1) dicotyledons, 2) monocotyledons
A) the presence of one cotyledon in the seed
B) fibrous root system
C) the presence of two cotyledons in the seed
D) reticulate venation of leaves
D) tap root system
E) parallel or arcuate veining of leaves
Answer
3. Establish a correspondence between the trait and the class of flowering plants for which this trait is characteristic: 1) Monocots, 2) Dicotyledons. Write numbers 1 and 2 in the correct order.
A) taproot system
B) one cotyledon
B) arc venation
D) parallel venation
D) three-membered flower
E) five-membered flower
Answer
4. Establish a correspondence between the characteristics and classes of angiosperms for which they are characteristic: 1) Monocots, 2) Dicotyledons. Write numbers 1 and 2 in the order corresponding to the letters.
A) tap root system
B) leaves with parallel veins
C) the number of flower parts is a multiple of 3
D) growth of the stem in thickness due to the cambium
D) characterized by intercalary growth
E) most species have a double perianth
Answer
5. Establish a correspondence between the characteristics of angiosperms and the classes for which they are characteristic: 1) Monocots, 2) Dicotyledons. Write numbers 1 and 2 in the order corresponding to the letters.
A) leaf venation is reticulate
B) leaf veining is parallel
B) thickening of the stem due to cambium
D) fibrous root system
D) three-membered flower
E) leaves simple and compound
Answer
FORMING 6
1) absence of cambium in the stem
Establish a correspondence between the characteristics of classes and plants: 1) shepherd's purse, 2) wheat. Write numbers 1 and 2 in the order corresponding to the letters.
A) flowers are pollinated by the wind
B) has a fibrous root system
C) leaves have developed vaginas
D) vascular bundles have a cambium
D) the number of flower parts is a multiple of four
E) the seed has two cotyledons
Answer
Establish a correspondence between plants and the families to which they belong: 1) Poaceae, 2) Rosaceae. Write numbers 1 and 2 in the correct order.
A) bamboo
B) pear
B) rye
D) strawberries
D) peach
E) oats
Answer
Choose one, the most correct option. The fruit pod is characteristic of members of the family
1) Rosaceae
2) legumes
3) nightshades
4) cruciferous
Answer
Choose one, the most correct option. The bean fruit is found in plants of the family
1) Asteraceae
2) nightshades
3) cereals
4) moths
Answer
Choose one, the most correct option. Why are shepherd's purse, wild radish, and mustard plants classified as members of the cruciferous (cabbage) family?
1) They have a tap root system
2) They have reticulate leaf venation
3) Their flowers are of the four-membered type, forming an inflorescence raceme
4) Their flowers are of a five-membered type, forming an inflorescence basket
Answer
Choose one, the most correct option. The main feature by which angiosperms are divided into classes is their structure.
1) flower
2) fetus
3) seed
4) stem
Answer
Choose one, the most correct option. In plants of the Cruciferous family: cabbage, radishes and turnips, the fruit
1) achene
2) box
3) pod
4) nut
Answer
Choose one, the most correct option. The main feature by which flowering plants are classified into one class is
1) structure of the fetus
2) method of reproduction
3) structure of the seed
4) living together
Answer
Choose one, the most correct option. A characteristic feature of a plant of the Asteraceae (Asteraceae) family is the inflorescence.
1) head
2) complex umbrella
3) simple umbrella
4) basket
Answer
Establish a correspondence between a plant trait and the family for which this trait is characteristic: 1) Brassicas, 2) Butterflies. Write numbers 1 and 2 in the order corresponding to the letters.
A) fruit pod or pod
B) inflorescence raceme
B) inflorescence raceme or head
D) flower formula CHB4L4T2+4P1
E) flower formula Ch(5)L1+2+(2)T(9)+1P1
E) bean fruit
Answer
Examine the picture and identify (A) the type of fruit depicted, (B) the family that the depicted fruit is representative of, and (C) its representatives. For each lettered cell, select the appropriate term from the list provided. Write down the selected numbers in the order corresponding to the letters.
1) pod
2) beans, acacia, peanuts
3) bob
4) cereals
5) cabbage, peas, henbane
6) moths
7) cruciferous
Answer
Establish a correspondence between the families of flowering plants and their characteristics: 1) Compositae, 2) Cereals. Write numbers 1 and 2 in the order corresponding to the letters.
A) family of the class Monocots
B) small flowers are collected in large inflorescences - baskets
B) fruit - achene
D) have a special cylindrical stem with well-developed nodes
D) the flower consists of two lemmas
E) family of the Dicotyledonous class
Answer
Look at the picture of a plant and indicate (A) the class, (B) the type of root system, and (C) the fruit. For each lettered cell, select the appropriate term from the list provided. Write down the selected numbers in the order corresponding to the letters.
1) monocots
2) grain
3) rod
4) dicotyledons
5) achene
6) fibrous
7) cob
8) cereals
Answer
Choose one, the most correct option. What role do legumes play in nature?
1) serve as food for humans
2) enrich the soil with nitrogen salts
3) are complete feed for livestock
4) nodule bacteria live on their roots
Answer
Find three errors in the given text. Indicate the numbers of the proposals in which they are made.(1) The division Angiosperms is divided into the classes Dicotyledons and Monocots. (2) Dicotyledonous plants are characterized by the presence of two cotyledons per seed. (3) Monocots have a ring of cambium in their stems. (4) A fibrous root system is usually characteristic of dicotyledonous plants. (5) Plants of the Poaceae and Liliaceae families are classified as Monocots. (6) Plants of the Rosaceae and Legume families belong to the Dicotyledonous class. (7) In dicotyledonous plants, as a rule, the number of flower parts is a multiple of three.
Answer
© D.V. Pozdnyakov, 2009-2019
Dicotyledons are the most numerous class of flowering plants (about 75%). The number of families in the class is more than 350. Representatives of the Dicotyledonous family have a similar flower structure.
IN family Rosaceae includes more than 3 thousand species. Among them are rose, cherry, raspberry, apple tree. There are woody, herbaceous forms and shrubs. The flower has a double perianth, a calyx of five free sepals, the same corolla, many stamens and pistils (raspberry, strawberry) or many stamens and one pistil (cherry, apple). The fruit is an apple, drupe, aggregate achene or drupe.
Among the Rosaceae there are many species that are used by humans. This fruit trees(apples, pears, apricots, plums, etc.), raspberries, strawberries. There are also a lot of ornamental plants (rose, sakura).
Family Legumes includes about 17 thousand species. Representatives of this family are peas, beans, lupine, soybeans, clover, acacia, peanuts, etc. Many of them are ancient cultivated plants. Feature leguminous plants is that they have nitrogen-fixing nodules on their roots. All legumes have compound leaves with stipules.
Legume flowers are irregular in shape; in a number of species, two petals are fused at the base. There are five petals in total and ten stamens. The fruit is a bean.
Leguminous plants are important food for herbivores (clover, alfalfa, vetch, camel thorn), there are medicinal plants, honey plants (clover, china, clover), ornamental plants ( sweet pea, lupine, acacia).
Family Cruciferae includes more than 3 thousand species, most representatives herbaceous plants, growing in the temperate zone of the Northern Hemisphere. Representatives of the cruciferous family are cabbage, radish, horseradish, mustard, rapeseed, shepherd's purse, heart, etc. Among the cruciferous plants there are many cultivated, medicinal, and ornamental plants, there are honey plants and many weeds.
A cruciferous flower consists of four sepals and petals, six stamens, four of which are long, and one pistil. The flowers usually form a raceme inflorescence. The fruit is a pod or pod.
Homeland of representatives Solanaceae family is America. Nightshades include potatoes, tomato, pepper, eggplant, petunia, nightshade, etc.
A nightshade flower has five sepals, petals and stamens, and one pistil. Sepals and petals fused. The fruit is a berry (potato, tomato) or capsule (petunia, tobacco).
Family Asteraceae- This is the largest family of the Dicotyledonous class. It has about 20 thousand species. Asteraceae are ubiquitous, most of their representatives are herbs. A special feature of Asteraceae are small flowers collected in inflorescences of a basket. Representatives of the Asteraceae are sunflower, cornflower, chamomile, coltsfoot, cornflower, and chicory. There are many honey and medicinal plants.
The calyx of Asteraceae flowers is most often absent; the corolla of five petals grows together and looks like a tube, tongue or funnel. The fruit is an achene or flying achene (dandelion).
Monocots (Monocotyledones) are a class of angiosperms of flowering plants, which has about 64,000 species, of which: 2,600 genera, 90 families. Monocots evolved from primitive herbaceous dicotyledons. Monocots include mainly annuals, biennials and perennial herbs, occasionally trees, vines and shrubs. Among the plants of this group there are many bulbous, wetland, and epiphytes. They grow on all continents. Monocots are a much more monolithic group than dicots.
Monocots got their name due to the characteristic feature that their embryo consists of only one cotyledon, which, while germinating, mainly remains inside the seed. With the help of this organ, the embryo absorbs from the seed nutrients(protein). 
Structure
Monocots have a fibrous root system. The main root usually stops growing after germination, and a system of adventitious roots begins to perform its function.
The flowers of such plants are three-membered, mostly bisexual (sometimes unisexual), come in different sizes, both large and small, and are collected in inflorescences. The flowers have a fused or free perianth, a calyx often corolla-shaped with six stamens (less often - fewer) and only one pistil. Monocots have a capsule-shaped fruit, sometimes a berry, and the seeds contain endosperm.
The stems of such plants branch very rarely, the stem vascular bundles are closed, and the vascular bundles in the stem have a random arrangement. The leaves are devoid of stipules, mostly cover the stem, narrow with parallel or arcuate veins. There is no cambium, so there is no thickening of the stems, as in dicotyledons or gymnosperms.
Monocots are divided into 7 orders:
1) Helobieae (family of algae, pondweed).
2) Spadiciflorae (palms, araceae).
3) Glumiflorae (sedges, grasses).
4) Enantioblastae (eriocaulonaceae).
5) Scitamineae (gingeraceae).
6) Liliiflorae (lily).
7) Gynandrae (orchids).
From monocotyledonous plants, humans produce the most important food products, namely: bread (wheat, rye, barley), rice, oatmeal and other cereals. Corn, onions, garlic, coconut and date palm fruits and other plants are also eaten. Ornamental plants are lily, tulip, hyacinth, narcissus, gladiolus, orchid. Many plants are used as livestock feed (oats, timothy, etc.). Bamboo – construction material. In addition, some monocots are harmful weeds.
