A shoot is an above-ground axial organ of a plant with the ability of unlimited growth and negative geotropism. A shoot is a stem with leaves and buds located on it. There are: vegetative shoots - shoots that typically perform the function of aerial nutrition; generative shoots (including the flower) shoots that ensure reproduction. Escape morphology
A vegetative shoot consists of a stem with leaves and buds. A node is the section of the stem from which a leaf (or leaves) arises. The area of the stem between two adjacent nodes is called internodes. Elongated shoots are shoots with long internodes. Shortened shoots are shoots with short internodes (apple and pear fruits). Escape morphology
The angle formed between the stem and the leaf is called the leaf axil. On the shoot you can find bud rings and traces of bud scales. The age of young shoots can be determined by the bud rings. After the leaf falls, a trace remains on the stem - a leaf scar. Escape morphology
The bud is a shortened embryonic shoot. There are vegetative, generative and mixed buds. Vegetative buds are buds from which shoots with leaves develop (in most plants). Inside the bud there is a rudimentary stem ending in a growth cone and rudimentary leaves. In the axils of the embryonic leaves, the rudiments of axillary buds are laid. Kidney structure
Generative (floral, reproductive) buds from which flowers or inflorescences develop. Vegetative-generative (mixed) buds, from which leafy shoots with flowers develop (apple, pear, lilac). Based on their location on the stem, the buds are: apical; lateral; axillary; subordinate clauses. Kidney structure
According to the nature of their location in space, shoots are distinguished: erect; ascending shoots, first growing horizontally and then vertically; creeping, growing more or less horizontally; creeping shoots that take root with the help of adventitious roots; curly, twining around a support; climbing shoots that have devices for holding on supports or on other plants (peas, grapes, ivy). Escape morphology
Monopodial if the growth cone functions for many years (the apical bud remains throughout the life of the plant and the growth of the main shoot in length occurs indefinitely). Sympodial if the apical bud dies off annually and is replaced by one of the nearest lateral buds (birch, poplar). Branching of shoots
Dichotomous if the growth cone is divided into two parts, each of which produces identical branches. False dichotomous: the apical bud dies, and two oppositely located lateral buds form two apical shoots (horse chestnut, lilac). The shoots can also be non-branching (dracaena, yucca, aloe, palm trees). Branching of shoots
Branching, in which lateral shoots develop from underground or ground buds of the mother plant, is called tillering. Typical for shrubs and cereals. In order for the fruits to grow better and ripen faster on the main shoot, pinching is carried out - removing unwanted side shoots (“stepchildren”).
Tuber formation occurs at the top of the underground stolon due to the activity of the apical meristem. Small filmy scale-like leaves quickly die and fall off, and in their place leaf edge scars form. In the axil of each leaf, in the recesses, groups of three to five buds appear. The buds are arranged spirally on the tuber. Buds are divided into apical and lateral. On a cross section of a potato tuber, you can find 4 layers: periderm, cambium, wood and pith. Modifications of shoots: underground shoots Tuber is a modified shoot, consisting of one or more metameres, the stem of which is greatly thickened. Performs a storage function, can be a regeneration organ for perennial plants, and often serves for vegetative propagation.
Modifications of shoots: underground shoots Rhizome, perennial underground (sometimes semi-submerged) shoot (lily of the valley, creeping wheatgrass, valerian, etc.). Performs the functions of renewal, vegetative propagation and accumulation of nutrients. Outwardly it resembles a root, but consists of metamers, has apical and axillary buds, and reduced leaves in the form of colorless scales. Nodes are detected by leaf scars and remains of dry leaves or by living scale-like leaves. Adventitious roots develop from stem nodes. Spare nutrients are deposited in the stem part of the shoot.
Bulb. It is a shortened, mainly underground shoot (onions, garlic, lilies). The stem part of the bulb (bottom) with greatly shortened internodes bears numerous succulent modified scale leaves. The outer scales quickly deplete, dry out and perform a protective function. Spare nutrients are deposited in the juicy scales. In the axils of the bulbous scales there are buds from which above-ground shoots or new bulbs are formed. Adventitious roots form at the bottom. The bulb can be annual (onion, kandyk) or perennial (narcissus, hyacinth). Modifications of shoots: underground shoots
Corm. It is a shortened shoot that looks like an onion (gladiolus, saffron, colchicum). It is an intermediate form between a tuber and a bulb. The bulk of the corm consists of a thickened stem part, covered with scaly dry leaves. A corm is formed by the growth and thickening of one or more internodes. In fact, a corm is a leafy tuber. On the axis of the corm, nodes, internodes and axillary buds are clearly visible. Modifications of shoots: underground shoots
1 - stem succulents; 2 – hawthorn spines; 3 – phyllocladies of butcher’s broom; 4 – asparagus cladodes; 5 - aboveground strawberry stolons; 6 – grape mustache. Modifications of shoots: above-ground shoots Cactus spines are modified leaves, barberry and acacia spines are stipules, honey locust and hawthorn spines are shoots, rose hip spines are outgrowths of the epidermis.
A head of cabbage is also a modified shoot - a giant modified bud that develops in the first year and accumulates nutrients in the leaves. It blooms, produces fruits and seeds the next year, and dies in the fall (cabbage is a biennial plant). Flowers of angiosperms and strobili of gymnosperms are also modified shoots that perform the function of sexual reproduction. Modifications of shoots: aboveground shoots
Already in the summer, a cork cambium phellogen is formed under the epidermis. It lays cork cells on the outside and phelloderm cells on the inside. Cork, phellogen and phelloderm form a common secondary cover, the periderm. Lentils are formed under some stomata. Anatomy of a woody plant stem
In a two to three year old linden branch, under the periderm there is bark (primary and secondary), cambium, wood and pith. Cambium. Located between secondary bark and wood. It is thanks to it that secondary changes occur in the structure of the stem. The cambium deposits a larger number of derivatives inside (into the wood) than outside (ratio 4:1, respectively). In spring, cambium cells actively divide; as autumn approaches, the activity of the cambium weakens, and in winter it enters a dormant period.
Bark. All tissues lying outward from the cambium are called bark. The secondary bark is represented by phloem (phloem) and medullary rays. The bast is formed by sieve tubes with companion cells, bast parenchyma and bast fibers. Organic substances move through sieve tubes. Nutrients accumulate in the bast parenchyma. Bast fibers provide strength. Anatomy of a woody plant stem
Wood. The composition includes vessels, tracheids, wood parenchyma and wood sclerenchyma (fibers). As a result of the periodic activity of the cambium in the wood, annual rings are formed, wood growth in one growing season. The age of a tree can be determined by the growth rings. The width of the growth rings is not the same: in favorable years, wider rings are formed than in unfavorable ones. Tropical plants that grow continuously throughout the year do not form growth rings. Anatomy of a woody plant stem
The stems of monocotyledonous plants do not have a secondary structure - the cambium is not formed, the vascular-fibrous bundles are closed (without a cambium), and are arranged randomly. Phellogen is not laid down, so there is no periderm. The stems of dicotyledonous herbaceous plants are characterized by the following features: the primary structure is early replaced by a secondary one; conductive bundles are arranged in an orderly manner - in a circle; vascular bundles are open type (have a cambium). Anatomy of the stem of herbaceous plants
A shoot is one of the main vegetative organs of higher plants, consisting of a stem with leaves, buds, inflorescences and fruits located on it. Performs the function of air supply, but often has a number of additional functions
The shoot grows due to the apical bud. It is a single organ of the same rank as the root, but has a more complex structure. Apical bud of white maple
The structure of a vegetative shoot A vegetative shoot consists of a Stem - the axial part, which has a cylindrical shape. Leaves are flat lateral organs sitting on the stem. Buds are the primordia of new shoots, ensuring the growth of the shoot and its branching. The main function of the shoot - photosynthesis - is carried out by the leaves; stems are primarily load-bearing organs that perform mechanical and conductive functions. yay
Features of the structure of the shoot Leafiness (The main feature that distinguishes the shoot from the root) Metameric structure. The section of the stem from which a leaf(s) arises is called a node. The areas of the stem between adjacent nodes are internodes. The first shoot of a plant is its main shoot (first order shoot). It is formed from an embryonic shoot ending in a bud (apical), which forms all subsequent metameres of the main shoot.
Lateral buds. In seed plants they are located in the axils of the leaves (axillary). They have exogenous origin. Lateral shoots develop from the lateral axillary buds, and branching occurs (increasing the photosynthetic surface, providing mechanical protection). Thus, a shoot system is formed. A shoot of any order has its own apical bud and is capable of growing in length.
A bud is a rudimentary shoot that has not yet developed. Inside the bud is the meristematic tip of the shoot - its apex. The apex is an actively working growth center that ensures the formation of all organs and primary tissues of the shoot. The vegetative apex of the shoot, in contrast to the always smooth apex of the root, regularly forms protrusions on the surface. Apical bud of an Elodea shoot: representing primordia A - longitudinal section; leaves. B – growth cone (appearance and longitudinal section); Only the B itself remains smooth - the cells of the apical meristem; G – tip of the apex, which the parenchyma cell has formed and is called the leaf cone; 1 – growth cone; 2 – rudiment of shoot growth. leaf; 3 – axillary bud rudiment.
Bud scales are modified outer leaves (protective function). Such buds are called closed (overwintering buds of trees and shrubs and some perennial herbs). Open buds do not have bud scales.
Adventitious or adventitious buds. They arise on the adult, already differentiated part of the organ endogenously, from internal tissues. Adventitious buds can form on stems (then they are usually located in internodes), leaves and roots. Biological significance: they provide active vegetative renewal and reproduction of those perennial plants that have them.
Root shoots are shoots that develop from adventitious buds on the roots. Reproduction by root suckers (raspberry) Kalanchoe Adventitious buds on the leaves immediately produce small shoots with adventitious roots, which fall off the mother leaf and grow into new individuals (broods).
The development of shoots from the buds in most plants is periodic. In many plants, buds develop into shoots once a year - in spring or early summer. Shoots that grow from buds in one growing season are called annual shoots, or annual increments. In summer, our deciduous trees only have annual shoots of the current year covered with leaves; There are no leaves on the annual shoots of previous years. In evergreen trees, leaves can be retained on the corresponding annual growths of the previous 3-5 years.
Buds that fall into a dormant state for some time and then produce new elementary and annual shoots are called overwintering or dormant. By function - kidneys regularly renew. Characteristic of perennial plants. If the lateral buds do not have a period of growth rest and develop simultaneously with the growth of the mother shoot, they are called enrichment buds. Functions: increase (enrich) the total photosynthetic surface of the plant, the total number of inflorescences formed, and seed productivity. Characteristic of most annual grasses
Dormant buds do not transform into shoots for a number of years, sometimes they do not turn into shoots at all. In most cases, the stimulating factor for the development of dormant buds is the death of the plant trunk.
In some plants, leafless flowering shoots are formed from dormant buds on the trunk. This phenomenon is called cauliflory and is characteristic of many trees in tropical forests. Jaboticaba Cocoa Judas Tree
Modified shoots Also, modified shoots can be formed from dormant buds. Shoots from dormant buds: 1 – cauliflory in a chocolate tree; 2 – spines of honey locust from branched dormant buds.
Direction of shoot growth. Shoots that grow vertically, perpendicular to the surface of the earth, are called orthotropic. Horizontally growing shoots are called plagiotropic. The direction of growth can change during shoot development.
Types of shoots by position in space A – erect; B – clinging; B – curly; G – creeping; D – creeping.
Leaf arrangement 1 – spiral in oak; 2 – diagram of spiral leaf arrangement; 3 – two-row in Gasteria (a – side view of the plant, b – top view, diagram); 4 – whorled in oleander; 5 – opposite for lilac. The order in which leaf primordia are formed at the apex of the shoot is a hereditary characteristic of each species, sometimes characteristic of a genus and even an entire family of plants.
Types of shoot branching Branching is the formation of a system of axes. It ensures an increase in the total area of contact of the plant body with the air, water or soil. Branching arose in the process of evolution even before the appearance of organs. There are two types of lateral branching: monopodial and sympodial A - dichotomous (moss); B – monopodial (juniper); B – sympodial of the monochazia type (cherry); G – sympodial of the dichazia type (maple).
1, 2 – diagrams of the structure of cushion plants; 3 – Azorella from Kerguelen Island. Plants with abundant branching: cushion plants. The growth of shoots in these plants is extremely limited, but every year many lateral branches are formed, diverging in all directions. Dionysia mossy
Representatives of the tumbleweed life form, characteristic of steppe plants, branch very strongly. The spherically branched, very loose system of shoots is a huge inflorescence, which, after the fruits ripen, breaks off at the base of the stem and rolls with the wind across the steppe, scattering the seeds.
parenchyma located between the vascular bundles gives rise to the interfascicular cambium, which differentiates into the parenchyma of the medullary rays. Thus, the fascicular and interfascicular cambium are connected and form a continuous cambial ring, but the fascicular structure is preserved. Conducting bundles in the stems of dicotyledonous plants, unlike monocotyledons, are arranged in a circle in one row. In some plants, the interfascicular cambium is weakly expressed; therefore, the secondary fascicular structure is not always clearly distinguished from the primary one. §A transitional structure occurs in plants whose stem in the primary structure also has a fascicular structure, but the secondary phloem and xylem are formed not only by the fascicular, but also by the interfascicular cambium. In this case, new conducting bundles appear, occupying space between the first ones. Gradually, the bundles close and a continuous ring of phloem, cambium and xylem is formed. Many dicotyledonous herbaceous plants have this structure.
In dicotyledonous plants, in the middle part of the procambial cord, the formation of cambium occurs and the formation of secondary conducting tissues (metalaema and metaxylem) begins, the volume of which increases due to the division of cambium cells. bundles with cambium, characteristic of dicotyledons, are open. Herbaceous monocotyledonous plants are characterized by a diffuse distribution of vascular bundles. The vascular bundles are closed, collateral, less often concentric. Of the mechanical tissues, sclerenchyma is the most developed; collenchyma is found in few plants. There is no secondary thickening in herbaceous monocots.
Conductive tissues in the stems of dicotyledonous plants are arranged in a ring around the core. The central cylinder can have a beam or non-beam structure. The vascular bundles are collateral or bicollateral, open. The presence of cambium causes secondary thickening of the plant stems. The bundles are separated by medullary rays, consisting of parenchyma and connecting the medulla with the pericycle or with the primary cortex. Mechanical tissues are located along the periphery, with sclerenchyma being part of the pericycle, collenchyma being part of the primary cortex. In the anatomical structure of dicotyledonous and gymnosperm plants, primary and secondary structures are distinguished. The primary structure is formed as a result of differentiation of the apical meristem, the secondary structure begins from the moment of cambium activity.
Specialization and metamorphosis of shoots. Shoots with normally developed internodes are called elongated. Their main function is to capture space and increase the volume of photosynthetic organs. auxiblast (elongated shoots) at the apex
Shortened shoots have close nodes and very short internodes. They form inside the crown and absorb scattered light penetrating there. Often shortened shoots of trees are flower-bearing and perform the function of reproduction.
In the course of adaptation to specific environmental conditions or due to a sharp change in functions, shoots can change (metamorphose). Shoots that develop underground are especially often metamorphosed. Such shoots lose the function of photosynthesis; Calamus marsh The most common underground metamorphosis of a shoot is a rhizome. A rhizome is usually called a durable underground shoot that performs the functions of deposition of reserve nutrients, renewal, and sometimes vegetative propagation.
Lily of the valley The rhizome is formed: Initially as an underground organ (kupena, raven's eye, lily of the valley, blueberry), First as an above-ground assimilating shoot, which then sinks into the soil with the help of retracting roots (strawberry, lungwort, cuff). Strawberries
When rhizomes branch, a clump of above-ground shoots is formed, connected by sections of the rhizome system. If the connecting parts are destroyed, the shoots separate and vegetative propagation occurs. A set of new individuals formed by vegetative means is called a clone. Rhizomes are characteristic primarily of herbaceous perennials, but are also found in shrubs (euonymus) and dwarf shrubs (lingonberries, blueberries).
Close to the rhizomes are underground stolons - short-lived thin underground shoots bearing underdeveloped scale-like leaves. Stolons serve for vegetative propagation, dispersal and territory capture. Spare nutrients are not deposited in them. Fireweed similar
In some plants (potatoes, pears), tubers form from the apical buds of stolons by the end of summer. The tuber has a spherical or oval shape, the stem is very thick, reserve nutrients are deposited in it, the leaves are reduced, and buds form in their axils. Cyclamen Tubers do not always develop on stolons. In some perennial plants, the base of the main shoot grows tuberously and thickens (cyclamen, kohlrabi cabbage). The functions of the tuber are the supply of nutrients, survival of unfavorable periods of the year, vegetative regeneration and reproduction.
Adenium In perennial herbs and subshrubs with a well-developed taproot, a unique organ of shoot origin, the caudex, is formed. Together with the root, it serves as a place for the deposition of reserve substances and bears many renewal buds, some of which may be dormant. The caudex is usually underground and is formed from short shoot bases that sink into the soil. Caudex differs from short rhizomes in the way it dies
A bulb is, as a rule, an underground shoot with a very short flattened stem - the bottom and scaly, fleshy, succulent leaves that store water and soluble nutrients, mainly sugar. From the apical and axillary buds of the bulbs, above-ground tulip bulbs shoots grow, adventitious roots are formed at the bottom Functions: organ of renewal and vegetative propagation Bulbs are most characteristic of plants from the families Liliaceae (lilies, tulips), alliums (onions) and amaryllis (narcissus, hyacinths)
The corm looks like a bulb, but its scale-like leaves are not storage; they are dry and filmy, and reserve substances are deposited in the thickened stem part (saffron, gladiolus). Crocus
Creeping tenacious If the stolons bear green leaves and participate in the process of photosynthesis, they are called lashes (drupe, creeping tenacious)
In strawberries, stolons lack developed green leaves; their stems are thin and fragile, with very long internodes. Such stolons, more highly specialized for the function of vegetative propagation, are called mustaches. Strawberries
Not only bulbs, but also above-ground shoots can be juicy, fleshy, and adapted to accumulate water, usually in plants living in conditions of lack of moisture. Water storage organs can be leaves or stems, sometimes even buds. Such succulent plants are called succulents. Leaf succulents store water in leaf tissue (aloe, agave, crassula, rhodiola, or goldenseal). Agave Aloe
Stem succulents are characteristic of the American cactus family and the African euphorbia family. The succulent stem performs a water-storing and assimilating function; leaves are reduced or turned into spines. stem succulent (cactus) The transformation of leaves into spines reduces the evaporative surface of the plant and protects it from being eaten by animals.
In many plants, the spines are not of leaf, but of stem origin (wild apple tree, wild pear tree). In hawthorn, the spines formed in the axils of the leaves are completely leafless from the very beginning. In honey locust, powerful branched spines are formed on the trunks from dormant buds. The formation of thorns of any origin is usually the result of a lack of moisture. Spines of various origins: 1 – leaf spines of barberry; 2 – spines of white acacia, modification of stipules; 3 – hawthorn spines of shoot origin; 4 – thorns – rose hip emergers.
The shoots of a number of plants bear thorns. Thorns differ from spines in being smaller in size; these are outgrowths - emergents - of the integumentary tissue and tissues of the stem bark (rose hips, gooseberries) Rose hip Gooseberry
Adaptation to a lack of moisture is very often expressed in the early loss, metamorphosis or reduction of leaves, losing the main function of photosynthesis. Then, the role of the assimilating organ is assumed by the stem. Sometimes such a stem of a leafless shoot remains externally unchanged (Spanish gorse, camel thorn).
in another case, the formation of such organs as phylloclades and cladodes occurs. These are flattened leaf-like stems or entire shoots. Butcher's broom Small, needle-shaped phyllocladies are formed in asparagus in the axils of the scale-like leaves of the main skeletal shoot. Asparagus
Some plants are characterized by the modification of leaves or parts thereof, and sometimes entire shoots into tendrils that twist around a support, helping the thin and weak stem maintain an upright position. In many legumes, the upper part of the pinnate leaf turns into tendrils (peas, peas, peas). Sweet pea tendrils
In other cases, stipules (sarsaparilla) turn into tendrils. Very characteristic tendrils of leaf origin are formed in pumpkins. Tendrils of shoot origin can be observed in grapes
Stem. Anatomical structure of the stem. The stem arises from the meristematic tip of the shoot - its apex. The apical meristem consists of constantly dividing initial cells. They give rise to all tissues and organs. As a result of the division of the primary meristems of the apex, the primary anatomical structure of the stem is formed: epidermis, primary cortex, central cylinder and pith
Stem development Primary vascular tissues develop from the procambium. The first elements of the phloem differentiate from the outer procambium cells located towards the periphery. Primary phloem is represented by thin-walled, short-lived elongated cells and is called protophloem, and its outer cells can be represented by mechanical fibers. The primary elements of xylem - tracheids, less often vessels with ringed and spiral thickenings of the walls - arise later from the internal cells of the procambium and are generally defined as protoxylem. In addition to conducting elements, it contains parenchyma cells. Later, it differentiates inward from the protophloem, having a more or less typical structure for phloem. Outside the protoxylem, metaxylem is formed, consisting of tracheids or trachea with thicker lignified walls. Thus, due to the activity of the procambium and the rest of the apical meristem, the primary structure of the plant stem arises.
Stem In dicotyledonous plants, in the middle part of the procambial cord, the formation of cambium occurs and the formation of secondary conducting tissues (metaphloem and metaxylem) begins, the volume of which increases due to the division of cambium cells. In monocotyledonous plants, the entire procambium is differentiated into elements of primary conducting tissues. The stems of monocots, especially herbaceous (cereals), have a simpler structure; they are characterized mainly by a primary structure. bundles with cambium, characteristic of dicotyledons, are open. Bundles consisting only of primary tissues, as in monocots, are closed-,
Structure of the stem of monocots Herbaceous monocots are characterized by a diffuse distribution of vascular bundles. The vascular bundles are closed, collateral, less often concentric. Of the mechanical tissues, sclerenchyma is the most developed; collenchyma is found in few plants. There is no secondary thickening in herbaceous monocots.
Stem of dicotyledonous plants The primary structure of dicotyledonous plants is expressed in very early phases of stem development. As a result of the activity of the cambium, it quickly turns into the secondary structure of the stem. The secondary structure of the stem can be of three types: bundled, transitional and non-fascicular. §The bundle structure is characteristic of plants whose procambium is formed in separate bundles. Their primary structure is fascicular. Later, a bundle cambium emerges from the procambium, forming elements of secondary phloem and secondary xylem in the bundles. The cells of the main parenchyma, located between the vascular bundles, give rise to the interfascicular cambium, which differentiates into the parenchyma of the medullary rays. Thus, the fascicular and interfascicular cambium are connected and form a continuous cambial ring, but the fascicular structure is preserved. Conducting bundles in the stems of dicotyledonous plants, unlike monocotyledons, are arranged in a circle in one row. In some plants, the interfascicular cambium is weakly expressed; therefore, the secondary fascicular structure is not always clearly distinguished from the primary one. §A transitional structure occurs in plants whose stem in the primary structure also has a fascicular structure, but the secondary phloem and xylem are formed not only by the fascicular, but also by the interfascicular cambium. In this case, new conducting bundles appear, occupying space between the first ones. Gradually, the bundles close and a continuous ring of phloem, cambium and xylem is formed. Many dicotyledonous herbaceous plants have this structure.
Anatomical structure of a herbaceous dicotyledonous plant. Conducting tissues in the stems of dicotyledonous plants are located in a ring around the core. The central cylinder can have a beam or non-beam structure. The vascular bundles are collateral or bicollateral, open. The presence of cambium causes secondary thickening of the plant stems. The bundles are separated by medullary rays, consisting of parenchyma and connecting the medulla with the pericycle or with the primary cortex. Mechanical tissues are located along the periphery, with sclerenchyma being part of the pericycle, collenchyma being part of the primary cortex. In the anatomical structure of dicotyledonous and gymnosperm plants, primary and secondary structures are distinguished. The primary structure is formed as a result of differentiation of the apical meristem, the secondary structure begins from the moment of cambium activity.
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Slide captions:
External structure and variety of leaves Let's consider how veins can be located in leaves; Let's learn to distinguish between simple and complex leaves.
External structure of a leaf: leaf base; petiole; leaf blade
Stipules stipules
Variety of leaves Leaves Presence of petiole Number of leaf blades Shape of the leaf blade Shape of the edge of the leaf blade Venation of the leaves Modifications of the leaves
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Based on the presence of petiole Leaf Petiolate Sessile
By the number of leaf blades Leaf Simple Complex
Compound leaves Leaf Pinnately Compound Palmately compound
Leaf blade shape Leaf blade Round Linear Broad-lanceolate
Shape of the edge of the leaf blade Leaf Entire edge Serrated Serrated
Leaf venation Leaf Reticulated Palmate Arc
Leaf modifications Leaf Cactus spines Pea tendrils Trapper apparatus
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Cellular structure of a leaf Why is the leaf green? How does he breathe? How does water enter it and how does it evaporate?
Integumentary tissue Structure Cells are tightly adjacent to each other. Functions Protective (gas exchange).
Stomata Guard cells Stomatal fissure
Stomata On the underside of the leaf On the upper plane of the leaf On both sides
Leaf (cross section) hairs cuticle skin
Importance of epidermal hairs Hairs Reduced evaporation Protection
Leaf (cross section) main tissue columnar tissue intercellular spaces spongy tissue vein
Leaf (cross section) bast vessels wood mechanical fibers
Functions of veins Veins Transport Support
Structure of leaf cell layers Pores surrounded by guard cells containing chloroplasts. Consists of colorless cells that secrete a waxy substance. Consists of loose and dense layers of cells containing chloroplasts. Represented by vessels, sieve tubes and mechanical fibers. Cell layers Names of cell layers skin flesh veins stomata Structure 2 3 4 1
Functions of leaf tissue cells Tissue cells protect the leaf from damage and external influences. 2. The process of photosynthesis occurs in tissue cells. 3. Tissue cells provide connection between the leaf and the stem, the movement of organic substances from the leaves to the stem, minerals and water from the stem to the leaf. 4. Cells provide gas exchange and water evaporation. Cell layers Names of cell layers skin flesh veins stomata Functions 1 2 3 4
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Bast sieve tubes satellite cells
Transport function wood vessels sieve tubes
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Well! Let's continue our journey. A shoot is a stem with leaves and buds located on it.
Shoots are divided into two types:
- vegetative,
- flowering.
On the flowering shoot, flowers develop from the buds, and on the vegetative shoot, leaves and stems develop.
In order to study in detail the structure of a vegetative shoot, consider a poplar branch without leaves. Do you see the buds on it? These buds are located throughout the stem,
and one decorates the very top, like the tip of a Christmas tree. This is the apical bud.
Those buds that are scattered along the stem are called lateral
Now look at that branch that we already looked at, but before the leaves fell from it in the fall. After all, your computer allows you to create such miracles!
- Do you see the buds located between the stem and the base of the leaf? This place is called the leaf axil, and the buds are called lateral or axillary.
- Did you know that there are knots in the shoot that no one has tied? It turns out that a node is the place on the stem from which the leaf and axillary bud extend.
The distance from one node to another is called the internode
Plant shoots can have different lengths of internodes.
Thus, in plantain or dandelion, the internodes are so small that they are practically indistinguishable, but in bamboo they can reach tens of centimeters.
Shoots of different plant species differ from each other not only in the length of the internodes. The location of the leaves on the stem can also be different. Leaf arrangement is the order in which the leaves are arranged on the stem. There are three main types of arrangement of leaves on the stem:
- next - one leaf comes off from each node of the stem: here is a shoot in which only one leaf is attached to each node. Such shoots can be seen in sunflower, rose hips, oak, linden, tradescantia, birch and other plants. This arrangement of leaves on the shoot is called alternate.
- opposite - two sheets are opposite each other,There are plants that have two leaves extending from the node, located opposite each other. This leaf arrangement is called opposite. We will see it in ash, lilac, maple, nettle, coffee tree, fuchsia.
- whorled - three or more leaves, they surround the stem in a ring. It also happens that a whole family of leaves sits on one internode, clasping the stem together. In this case, the leaves are said to form a whorl, and the leaf arrangement is called whorled. The whorl may have 4 leaves, like the forest plant crow's eye, or maybe more. Such whorls are found in Elodea, an aquatic plant that many people keep in their home aquarium.
In order to learn the secrets of the arrangement of leaves on the stem, let's think about the importance of the shoot for the entire plant. It turns out that the most important “job” of vegetative shoots is to create organic nutrients (sugars, starch and others) from... carbon dioxide and water. Yes Yes! And the sun helps them in this, giving part of its energy. This complex process was called aerial nutrition of the plant.
Aerial nutrition of plants is the process of creating complex organic substances from carbon dioxide and water under the influence of sunlight. Knowing about aerial nutrition of plants, we can now talk about another secret of leaf arrangement
Leaves. They play the main role in air nutrition. Therefore, the leaf surface should receive as much sunlight as possible. But what to do when there are thousands of leaves on a tree that can shade each other? Look! It turns out that the leaves are arranged so that there is enough light for everyone. This is the so-called sheet mosaic.
- On this birch branch, the alternate leaves turn towards the light so that everyone gets the light.
- Here's another trick. In many plants, the leaves on the stem are arranged in a spiral rather than in one plane. This way they don't block each other's sun. In this case, the main leaf arrangement can be alternate, opposite or whorled.
With any type of leaf arrangement (alternate, opposite, whorled), the leaf turns towards the light so that the sun's rays are available to the rest of the leaves
Let's see where they grow: some up, some sideways, some “stand firmly on their feet,” and some are looking for support. According to the direction of growth and location in space, shoots are divided into: creeping, recumbent, climbing, climbing, clinging.
- Upright escape. In an erect shoot, the stem grows perpendicular to the surface of the earth.
- Creeping escape. In the creeping plant, the stem spreads along the surface of the soil.
- Curly shoot. In a climbing plant, the stem wraps around a support.
Climbing escape. In climbers, the stems are weak, attached to the support with the help of thin curly tendrils
Plant shoots not only rise high above the surface of the earth and spread across it in different directions. They grow just as well underground. Underground modifications of shoots are:
- rhizome (rhizome is usually called a more or less durable underground shoot, usually devoid of normally developed green leaves);
- tuber (nutrients are deposited in tubers);
Bulb (modified underground shoot, accumulates a supply of nutrients in leaf scales
plant leaf
- The main part of the leaf is usually flat and expanded. It is called the leaf blade.
- Most leaves have a petiole that extends from the leaf blade. It is much narrower than the leaf blade and looks like a stalk. The petiole can change its position in space, while rotating the leaf blade. This is especially visible when the leaves sway even in a light wind. It is thanks to the petiole that the leaf can turn its leaf blade towards the light so that it receives as much sunlight as possible.
The place where the petiole attaches to the stem is always slightly expanded. This is the base of the leaf
Look at the clover leaf. What is this? At the base of the leaf, tightly pressed against the petiole on both sides, two small leaves lurk. This is also part of the leaf. Such outgrowths at the base of the leaf are called stipules. They can have very different shapes and colors. Stipules are not found on all leaves.
Based on the presence or absence of a petiole, leaves are divided into petiolate and sessile.
- Perhaps you have seen that in some plants the leaf blade “sits” on the stem without any petiole. Such leaves are called sessile. Sessile leaves can be seen in cloves, flax, wheat, and tradescantia.
Plants that have a petiole are called petiolate
Now compare the leaves of birch and rowan. Look: a birch leaf has one leaf blade, and a rowan leaf has eleven. Yes Yes! This is not a twig, but just one leaf. Take a closer look, the rowan leaf blades do not sit on the stem, but on the petiole, because at its base you can see stipules.
- Leaves with one leaf blade are called simple. Birch leaf - simple.
Leaves with several leaf blades on the petiole are compound. Rowan leaf - complex
Now let's take a closer look at the different leaves. You can even hold them up to the light. You can probably already guess what we're going to talk about! Of course, about that wonderful lace pattern that is formed by the veins of the leaf. This is called leaf venation.
- Have you ever found last year's aspen leaf on the ground in the forest? This is an amazing lace miracle! All soft leaf tissues rotted over the winter. All that remained was the thinnest mesh of stronger veins. This venation is called reticulate.
- Now hold the maple leaf up to the light. Do you see that the large veins radiate from one point near the petiole? This is palmate venation.
Let's take another sheet. Let it be plantain or lily of the valley. Do you see how all the veins, except the central one, are curved like arcs? This venation is called arcuate
A change in the external structure of leaves is called their modification. It is due to the fact that the leaf performs functions that are not usually characteristic of it, adapting to environmental conditions.
- Look at the prickly cactus. Where are its leaves? They turned into dry, hard thorns to reduce water evaporation. After all, cacti grow in very dry areas.
- And in peas, the upper leaf blades of the pinnate leaves have become tenacious, graceful tendrils.
But these are some really amazing leaves. They know how to catch and eat animals. There is a sundew in front of you. This plant is a predator. Do you see how sundew leaves are covered with hairs that secrete droplets of a special sticky substance? Having sat on such a leaf, the insect simply sticks to it. Then the leaf begins to shrink, tightly “hugging” its victim. When the leaf opens again, only the wings and legs of the former fly remain on the leaf. The sundew digests and absorbs all the soft tissues of the insect.
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Slide captions:
The structure of an escape What is an escape?
Plant shoot A shoot is a stem with leaves and buds located on it.
Types of shoots Shoot Vegetative Flowering
Vegetative shoot apical bud lateral buds
Vegetative shoot leaf axil node internode
Internode size
Leaf arrangement Leaf arrangement Alternate Opposite Whorled
Air power
Sheet mosaic
Thank you for your attention
Regular leaf arrangement Regular leaf arrangement - one leaf emerges from each stem node. https://accounts.google.com
Slide captions:
The structure of a flower We will not only admire the beauty of flowers, but also study their structure.
Flower – organ of seed propagation of plants
Variety of colors
Flower structure Flower Corolla Calyx Stamens Pistil Receptacle Pedicel Perianth
Unisexual and bisexual Flowers Unisexual Bisexual Pistillate female ♀ Staminate male ♂
Monoecious and dioecious Flowers Monoecious Dioecious
Thank you for your attention
Corolla Corolla Separately petaled
Calyx Calyx Composite Split-leaved
Perianth Perianth Double Simple
Perianth sepals petals stamens pistils
Location of ovules
Flower diagram and formula 1 P 5 T 5 L 5 H
Flower diagram and formula
Flowers and fruits
Pollination is the transfer of pollen from the stamens to the stigma. Pollination
Pollination methods Pollination Self-pollination Cross
Select the desired characteristics Flowering: occurs in early spring; occurs in late spring; happens in summer. Plant Rye Linden Lily of the valley Elderberry Beetroot Dandelion Alder Flowering 3 3 2 3 3 2 1
Select the desired characteristics Pollination: the plant is insect-pollinated, has bright flowers, secretes odorous substances and nectar, flowering is associated with the time of flight of insects; the plant is self-pollinating, has closed flowers or pollination occurs in the bud; the plant is wind-pollinated, has small, inconspicuous flowers, the perianth is often reduced to scales. Plant Rye Linden Lily of the valley Elderberry Beetroot Dandelion Alder Pollination 3 1 1 1 1 2 3
Thank you for your attention
Pollen Elm Fir Skerda Alder Centipede Moss moss
Self-pollination
Cross pollination Insect pollination Wind
Signs of insect-pollinated plants Large flowers, or small, but collected in inflorescences Bright color of the corolla Aroma and nectar
Signs of wind-pollinated plants Small, inconspicuous flowers Without aroma and nectar There is a lot of pollen, it is light, small and dry
ESCAPE AND KIDNEYS
Lesson objectives: form the concept of a bud and shoot, the structure of vegetative and generative buds, develop the concept of tissues; based on observations of shoot development, reveal the essence of the processes of plant growth and development.
Equipment: experimental plant: shoots of poplar, elderberry, maple, currant with blossoming buds. Tables “Escape, bud structure”; magnifiers, laboratory equipment.
Equipment: indoor plants with alternate, opposite, whorled leaf arrangement; annual shoots of poplar, elderberry, currant, maple; blossoming buds with vegetative and generative shoots (lilac, poplar or cherry); tables “Leaf arrangement”, “Location of buds on the shoot”; microslide “Growth cone”, microscope.
Tasks: form an idea of the shoot as a complex plant organ; show,
Whatbud - embryonic shoot; explain the order of the buds on the shoot, give
concept of vegetative and generative buds, their structure and adaptability to
environmental conditions.
Planned learning outcomes
Students should know:
- escape detection;
- what is called a node, internode, leaf axil;
- which plants have alternate, and which have opposite and whorled leaf arrangement;
- how does the apical bud differ from the lateral bud;
- what is leaf scar?
- kidney structure;
- due to what shoot growth occurs;
- where plants may have accessory buds;
- the difference between vegetative and generative buds. Students should be able to:
- distinguish between apical and axillary buds;
- be able to identify vegetative and generative buds;
- determine the types of leaf arrangement on herbarium specimens, in indoor plants, in drawings and in living plants in forests, gardens, parks, squares;
- explain the reasons for the growth of the shoot in length.
During the classes
I . Check of knowledge.
1) What plants produce roots?
2) From what parts of the root do root tubers develop?
3) In what conditions do plants with aerial roots live?
4) From what parts of the plant do modified roots - root crops - develop?
5) What plants form root tubers?
6) What is the meaning of anchor roots?
7) What modified roots develop in mangrove plants?
8) What other interesting modifications of roots do you know?
Slide 3 (Test 5 min)
Slide 2 (check)
Learning new material.
Form concepts and practice them during explanation using herbarium
material, tables, pictures in the textbook.
A shoot-stem with leaves and buds located on it.
Kidney - rudimentary shoot.
Vegetative (leaf) a bud is a rudimentary leaf on a rudimentary stem.
Generative (floral) a bud is a rudimentary bud on a rudimentary stem.
Slide 3
P - I was the first to get out of the mud on a thawed patch. He is not afraid of frost, even though he is small.
Slide 4
O - There is one such flower, You cannot weave it into a wreath. Blow on it lightly, There was a flower - and there is no flower.
Slide 5
B - Sticky buds, Green leaves, With white bark Stands above the mountain.
Slide 6
E - You will always find her in the forest - Let's go for a walk and meet her. Stands prickly, like a hedgehog, in a summer dress in winter.
Slide 7
G - My stem is thin and tall, Flower, flower, more flower. I reach up to the sun and keep growing, growing, growing.
( snowdrop)
( dandelion)
( birch)
( spruce)
( gladiolus)
Slide 8
The guessed words and their images appear on the screen (slides 2,3,4,5,6), (slide 7) the words are lined up in a column. It turns out the word ESCAPE.
Slide 9 Lesson topic
Slide 10 Lesson Objectives
Slide 11
The escape - This ….
Slide 12
Escape structure
1st place of leaf development on the stem area is called -knot
2 – internode – distance between two nodes on the shoot
3- angle between the leaf and the internode located above -leaf axil
1 - apical bud (at the top of the shoot)
2 – axillary (buds in the leaf axil)
3 – accessory buds (on internodes, leaves, roots)
Slide 13
apical bud
internode
lateral, or axillary,
bud
leaf axil
Slide 14
Teacher's story.
The main shoot develops from the apical bud, due to which the plant
stretches out in length. Lateral shoots develop from the axillary buds, due to them
the plant grows in breadth.
Using the table and living objects, study the leaf arrangement of plants.
Most plants have alternate, or spiral, leaf arrangement.
Regular Opposite Whorled
Slide 15
The opposite is less common:lilac, flax, horse chestnut, elderberry. Whorled
the arrangement of leaves (and buds) is characteristic of many tropical plants, therefore
it can be observed in indoor plants:oleander, asparagus.
Whorled leaf arrangement also occurs inhoneysuckle
Slide 16
Invite students to sketch examples of shoots with alternate, opposite and
whorled leaf arrangement.
Question to the class:
Slide 17 Kidney
- How do kidneys manage to survive adverse conditions?
Examine a horse chestnut bud. What is the role of protective scales? What is located
under them? Explain how vegetative buds differ from generative ones. Exercise
students in determining generative and vegetative buds by external signs.
Slide 18 Kidney structure
Slide 19 Types of kidneys
Slide 20 Physical education minute
Slide 21
2. Laboratory work “Structure of the kidney. Location of buds on the stem"
(p. 102 of the textbook). Instruction card
find and consider the growth point.
Slide 22 Invite students to examine a microslide"Cone of bud growth"
consider the growth point.
Explain the rolegrowth cone in the processes of shoot growth and development of shoots from the bud.
Slide 23 Teacher's story.
The cells of the educational tissue make up the growth cone. Stem growth depends on environmental conditions. And yet, the intensity of stem growth among plants varies. Thus, a corn stalk grows up to 4 m over the summer;
Slide 24 a bamboo stem can grow 1 m in a day; a young eucalyptus stem grows 3 m per year; apple trees and poplars - up to 1 m.
Slide 25 Topiary art
By pruning shoots, you can shape the crown of trees. Fruit trees are pruned by removing vegetative shoots that shade generative ones, as well as excess generative ones.
Two thousand years ago in China, excess ovaries were knocked down with sticks to get a good harvest of fruit. By pruning you can speed up or slow down the flowering of ornamental plants.
III . Consolidation of what has been learned. Test
1) What is called an escape?
2) What is the importance of shoots in plant life?
3) What is a kidney?
4) What is the structure of the kidney?
5) How do vegetative (leaf) buds differ from generative (flower) buds?
6) What causes shoot development?
Homework: § 22.
Reflection
1. Escape develops from... 1) root; 2) stem; 3) kidneys.
2. 1) nodes; 2) internodes.
3. 1) kidney; 2) new shoot; 3) leaf scar.
4.
1)
5. The buds of plants in the temperate zone, as a rule,... \) do not have kidney scales;
2) have kidney scales.
6.
7. The spaces between the leaves on a shoot are called... 1) nodes; 2) internodes.Check: 1 -3; 2 -1; 3 -3; 4-1; 5- 2; 6-3; 7-2.
Annex 1
SUBJECTLesson "Escape and Buds"
Laboratorywork “Structure of the kidneys.
Complete the definition:
They call it an escape –…….
Sign the escape parts
Laboratory work “Structure of the kidneys. Location of buds on the stem”, sketch the location of the buds on the stem.
Label the parts of the kidneys in the picture. Indicate which of them is vegetative and which is generative.
What adaptations help the kidneys withstand adverse conditions?
Finish filling out the diagram:
Types of kidneys
By structure
By location on the stem
Kidney structure
vegetative
generative
6). Look at the drawing. Compare the structure of the bud and shoot. Connect with arrows the corresponding parts of the bud and shoot.
Conclusion:
Appendix 2
Test
1. Escape develops from...
1) root; 2) stem; 3) kidneys.
2. The places where leaves are attached to the shoot are called... 1
) nodes, 2) internodes.
3. After the leaf falls, what remains in its place on the shoot is... ;
1) point; 2) new shoot; 3) leaf scar.
4. The buds from which shoots with leaves are formed are called...
1) vegetative; 2) generative.
5. The buds of plants in the temperate zone, as a rule,
1) do not have kidney scales; 2) have kidney scales.
6. From the bud on the shoot appear... 1) root; 2) leaf; 3) new escape.
7. Gap between the leaves on the shoot are called...
1 ) nodes; 2) internodes.
Life activity and modifications of roots. Soils and fertilizers
1. Three tomato plants were fertilized with different fertilizers for a week. The following results were obtained: the 1st plant grew by 20 cm in a week; The 2nd plant grew by 13 cm; The 3rd plant grew by 14 cm. Which of the plants was fertilized with nitrogen fertilizers: a) first; b) second; c) third?
2. Root vegetables are formed from:
a) lateral and adventitious roots; b) tank roots and stem;
c) main root and part of the stem; d) adventitious roots and parts of the stem.
3. From lateral or adventitious roots the following are formed:
a) root vegetables; b) root tubers; c) bulbs; d) root vegetables, root tubers, bulbs.
4. Modified roots are used for:
a) storage of nutrients; b) air breathing;
c) storing water; d) for storing nutrients and water, air
breathing.
5. The "supports" of the banyan tree, extending from its branches, - This:
a) main roots; 5) lateral roots; c) adventitious roots; d) all types of roots.
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Slide captions:
Biology lesson in 6th grade Topic: Escape and buds. External structure of the leaf.
Lesson objectives: Structure of the shoot Features of leaf arrangement Structure of the buds Structure of the leaf blade
Leaf arrangement Regular Opposite Whorled
Stem Buds Leaves Structure of the shoot The shoot is one of the main organs of higher plants. The shoot consists of an axis - the stem - and leaves and buds extending from it.
Structure of a vegetative bud 1 - rudimentary leaves; 2- growth cone; 3- rudimentary buds; 4- rudimentary stem; 5- kidney scales.
The structure of the generative (flower) bud 1 - rudimentary leaves; 2- growth cone; 3- rudimentary buds; 4- rudimentary stem; 5- kidney scales; 6- rudimentary flowers.
When the apical bud is removed, many side shoots are formed. This property is used in gardening, horticulture and floriculture. Plant growers pinching the top of the shoot force it to branch more.
1-lilac; 2-apple tree; 3-maple; 4-clover; 5-dandelion; 6-rosehip; 7-raspberry; 8-strawberries; 9-lupine. Simple and compound leaves
Leaf venation
Questions for consolidation What is an escape? What parts does it consist of? What types of leaf arrangement do you know? What is a kidney? How are kidneys identified? How are the buds located on the shoots? What is the structure of a vegetative bud? How do generative buds differ from vegetative buds? How does a shoot grow in length?
Your opinion about the lesson - What topic did you learn about during the lesson? - Were you interested in the lesson? - What did you learn new in the lesson? - Do you think knowledge about escape will be useful in your life? - How would you rate your participation in the lesson?
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