Significance of plant anatomy

vegetable anatomy

The cells in the first part

1. Cell wall: including intercellular layer (pectin), primary wall (cellulose, hemicellulose and pectin with great plasticity) and secondary wall (cellulose, hemicellulose and lignification).

2. Plastids: chloroplasts, chromosomes, leucosomes (amyloplasts, oil-forming bodies).

3. Vacuole: contains sugars (stems of sugarcane and roots of beet), organic acids, tannins (tea and persimmon), alkaloids (morphine in poppy and caffeine in coffee) and anthocyanins (red, blue and purple, which are related to pH value).

4. Microtubules: maintaining cell morphology; Participate in the formation and growth of cell walls; It is related to the movement of cells.

5, microfilament: maintain cell morphology; Control the movement of organelles; Related to cytoplasmic flow.

Section 2 Organizational structure

I. Definition:

There are many cells with similar morphology, the same structure and function, which form a cell group.

Second, the classification:

Meristem: located in the growth part of plants, it can maintain strong division ability continuously.

protective tissue

Mature tissue: differentiated from meristem cells and parenchyma.

Generally speaking, mechanical tissues are no longer divided and differentiated.

Conductive tissue

secretory structure

Section III Vegetative Organs (Roots) of Seed Plants

1. is composed of various tissues, which have obvious morphological characteristics and specific functions in appearance and are easy to distinguish.

This is called an organ

In the vegetative growth period, the whole plant can be divided into three organs: root, stem and leaf, which are called vegetative organs. The following is divided into three parts:

Second, the root

Physiological function and economic utilization of 1) root;

1, role:

Absorb (water, inorganic salts)

To fix and support (solid mechanical tissue).

Conduction (vascular tissue)

Synthetic ingredients (amino acids, growth hormones, plant alkaloids: for example, with medicinal value)

Storage (developed parenchyma)

Propagation (cutting roots in vegetative propagation)

2. Economic utilization rate:

Edible (sweet potato, carrot, radish, beet)

Medicinal (Ginseng Radix, Radix Angelicae Sinensis, Radix Glycyrrhizae, Radix Gentianae)

Arts and crafts (beetroot can be used as raw material and root art for sugar production)

Others (protecting river banks to prevent soil erosion)

2) the type of root

1, taproot, lateral root and adventitious root

2. Straight root system and fibrous root system

3. Deep root system and shallow root system

3) the structure between roots

The root tip refers to the section from the top of the root to the hair root. It is the most vigorous and important part of the root. The elongation of the root, the absorption of water and nutrients by the root and the formation of tissue in the root are mainly formed at the root tip. The root tip can be divided into four parts: root cap, meristem, elongation and maturity.

4) Primary structure of roots

Epidermis, cortex, vascular bundles

V) the secondary structure of roots

The roots of annual dicotyledonous plants and most monocotyledonous plants have completed their lives through primary growth, but the roots of most dicotyledonous plants and gymnosperms have experienced secondary growth and formed secondary structures.

After primary growth, the vascular cambium (lateral meristem) begins to divide tangentially between primary xylem and primary phloem. After division, growth and differentiation, the number of vascular tissues in roots increases. This growth process is the result of vascular cambium activity, which makes the roots thicker and is called secondary growth. Because the roots become thicker and the epidermis is broken, another kind of lateral meristem-cork cambium appears, forming a new protective tissue-periderm to replace the epidermis. The secondary vascular tissue and periderm together constitute the secondary structure of roots.

6) Formation of lateral roots

The lateral root originated from the stele sheath and connected with the vascular tissue of the mother root.

7) Nodules and mycorrhiza

Section 4 Vegetative Organs (Stems) of Seed Plants

Stem is an axial structure that connects roots, stems and leaves, and transports water, inorganic salts and organic nutrients.

I. Physiological Function and Economic Utilization

1, physiological function: transportation (xylem and phloem)

Support (mechanical tissue: fibers and stone cells)

Storage: parenchyma cells of rhizome (lotus root), bulb (arrowhead) and tuber (potato)

Propagation (cutting, layering)

2. Economic utilization: food (sugarcane, potato, taro, water bamboo, lotus root, arrowhead, ginger)

Medicinal materials (Gastrodia elata, Polygonatum sibiricum)

Others (rubber, wood, bamboo)

Second, the morphological characteristics of the stem

The main differences between stems and roots in appearance are: stems have nodes and internodes, leaves are placed on nodes, and leaves are placed in leaf axils and at the top of stems. Stems with leaves and buds are called branches. Therefore, the stem is the shaft of the branch after the leaves and buds are removed.

Third, the bud and the kind of bud

1. The concept of bud: a bud is a branch, flower and inflorescence that is in its infancy but not stretched, that is, the embryonic body before the development of the branch, flower and inflorescence. So it can be divided into flower buds and branch buds.

2. The general structure of bud: apical meristem, Yuan Ye basal part, young leaves and axillary bud primordium.

3. Classification of buds

1) According to the position of buds on branches, they can be divided into fixed buds and indefinite buds.

2) According to the existence of bud scales, it can be divided into naked buds and lateral buds.

3) According to the nature of buds, the formed organs are divided into branch buds, flower buds and mixed buds.

4) According to the physiological activity of buds, there are active buds and dormant buds.

(4) the growth mode of the stem

1, erect stem: Most plants have such a stem.

2, winding the stem: the stem is soft and cannot stand upright, and the stem itself can be wound on other plants to rise. Such as Petunia, Aristolochia and Polygonum Multiflori Radix.

3, climbing stem: the stem is soft, can not stand upright, has a unique structure can climb other things.

1) Climb with tendrils: loofah, peas, cucumbers, grapes and pumpkins.

2) Climbing with aerial roots: Ivy

3) Climbing with petiole:

4) Climbing with hook: pig gizzard

5) Climbing with sucker: Parthenocissus tricuspidata

Plants with twining stems and climbing stems are collectively called lianas, which are particularly flourishing in tropical forests and subtropical forests.

4. Stolon: The stem is slender and soft and grows along the ground. Such as strawberries and sweet potatoes. Generally, the internodes are long, and adventitious roots can be born on the nodes, which can reproduce.

(5) Branch mode

1, uniaxial branch:

2. Axis branch:

3, false binary branch:

(VI) Tillers of Gramineae Plants

The branching of Gramineae plants is different from the above, which produces axillary buds on underground and near-surface rhizomes, and then axillary buds form branches with adventitious roots. This branch is called tillering. Tillers can continue to form on tillers, and the first tiller and the second tiller can be formed in turn.

(7) Primary structure of stem

1, Primary Structure of Dicotyledonous Stem:

(1) Epidermis: It is usually a single layer, which is developed from the original epidermis and has a protective effect. Generally, it does not have chloroplasts, and some contain anthocyanins (such as purple stems of sugarcane). The tangential wall exposed to air is relatively thick, keratinized or waxy, and has pores.

(2) Cortex: differentiated from ground meristem and located between epidermis and vascular column. It is mainly composed of parenchyma and intercellular space.

Cortical cells near the inside of epidermis often differentiate into thick horn cells, which have a supporting role.

(3) Vascular column:

Including vascular bundles, pith and pith rays, without stele sheath.

2. Primary structure of gymnosperms stems:

It is basically similar to dicotyledonous plants, including epidermis, cortex and vascular column, and consists of vascular bundle, pith and pith rays.

The main differences are: 1) xylem is tracheid and phloem is sieve cell.

2) There are no grass stalks, only woody stems. So gymnosperms all enter the secondary stage after a short primary stage.

3. The primary structure of monocotyledonous stems:

The stems of most monocotyledonous plants have only primary structures, so their structures are relatively simple. The epidermis has pores; The basic tissue is composed of thick-walled tissue, which plays a supporting role; Vascular bundle is composed of xylem and phloem, without cambium. The differentiation of phloem in vascular bundle is initiated externally, and the differentiation of xylem is initiated internally, which is the characteristic of stem.

(8) The secondary structure of the stem (this part is similar to the secondary structure of the root)

1. The secondary growth of stem is mainly due to the differentiation of lateral meristem, which includes vascular cambium and cork cambium.

When the cambium begins to move, the cells divide tangentially, forming secondary phloem cells outward and adding them to the inner side of the primary phloem; Secondary xylem cells are formed inward and added outside the primary xylem.

2. Early wood and late wood: in temperate and subtropical spring, the temperature is high, the water is sufficient, the cambium activity is vigorous, and the secondary xylem cells formed are large in diameter and thin in wall, which is called early wood; In autumn, the activity of cambium is weakened, and the cells formed are small in diameter and thick in wall, which is called late wood. Early wood is loose in texture and slightly light in color; Late wood is dense in texture and dark in color.

3. Tree rings: In a growing season, early wood and late wood * * * form a remarkable concentric ring layer, representing the secondary xylem formed in a year. However, some plants form more than one annual ring in a year's normal growth, which is called false annual ring.

4, heartwood and sapwood:

Heartwood is the inner layer of secondary xylem, that is, early secondary xylem. Nutrients and oxygen are difficult to enter, and tissues will age and die. Therefore, ducts and tracheids often lose their conduction function and deposit substances such as resin, tannin and oil. The heartwood of some plants is hard and wear-resistant and has a special color.

Sapwood is a part of the secondary xylem with light color around heartwood, which has the function of grooming and storage and can be gradually transformed into heartwood. Therefore, heartwood increases year by year, and the thickness of sapwood is relatively stable.

The fifth leaf

Leaf is an important organ for seed plants to produce organic nutrients, and it is also the main place for photosynthesis.

I. Physiological Function and Economic Utilization of Leaves

Physiological function: 1. Photosynthesis: The process by which green plants absorb light energy, synthesize organic matter with carbon dioxide and water, and release oxygen.

2. Transpiration: The process that water passes through the surface of living plants from the body in gaseous state and is lost to the atmosphere.

Transpiration is of great significance to plant life activities;

1) is one of the driving forces of water absorption and transportation.

2) Conducive to the transportation of mineral elements.

3) The surface temperature of the blade can be reduced.

3. Absorption function: For example, fertilization outside the roots, spraying a certain concentration of fertilizer on the leaves can be absorbed on the surface of the leaves.

4. Reproductive capacity: (vegetative reproduction)

Economic utilization ratio: 1. Edible: Green vegetables, spinach and leeks.

2, medicinal: mint

3. Others: the fiber in sisal leaves can be used for papermaking, tea can be used as beverage, and tobacco can be used for cigarettes.

Second, the shape of the leaves.

1. Composition of leaves: Leaves of plants are generally composed of leaves, petioles and stipules.

2. Pulse sequence: Pulse sequence is mainly divided into three types: parallel pulse, reticular pulse and fork pulse.

3, single leaf and compound leaf:

4. Leaf order: generally, there are three kinds: alternate, opposite and alternate.

Third, the structure of leaves.

1, epidermis

2. mesophyll

3. Texture

Fourth, the structure of leaves.

1, leaves of xerophytes and aquatic plants

2. Leaves of shade plants and sun plants:

Five, deciduous trees and evergreen trees

Section 6 Abnormal situation of plant organs

A plant organ has changed its shape and structure because it has adapted to a special environment and changed its original function. After long-term natural selection, it has become the characteristic of this plant. This change in the general shape and structure of plant organs caused by functional changes is called metamorphosis.

First, the root of abnormal condition.

1, storage root:

1) fleshy taproot: taproot is developed, such as radish, carrot and beet.

2) tuberous root: developed from adventitious roots or lateral roots, such as sweet potato (sweet potato)

2, aerial roots: roots that grow in the air above the ground.

1) Column root: adventitious root, such as corn.

2) Climbing roots: Ivy (the stems are too weak to stand upright)

3) Breathing roots: mangrove trees by the sea and water cypress by the pool. There is ventilation tissue in it, which is beneficial to ventilation and gas storage.

3. Parasitic roots: For example, dodder, the stems are tightly wound on the parasitic stems, the leaves are degraded, and the nutrition is completely dependent on the host. The extended roots extend into the tissues of the host stems, communicate with the vascular tissues of the other side, and absorb nutrients and water from the host.

Second, the abnormal situation of the stem

1, aboveground stem:

1) stems: hawthorn, Gleditsia sinensis.

2) Stems and vines: grapes, pumpkins and cucumbers.

3) leaflike stem:

2, underground stem:

1) Rhizomes: bamboo, lotus and reed.

2) tuber: potato

3) Bulbs: Lily, onion and garlic.

4) Bulbs: water chestnut, arrowhead and taro. (with degenerated and abnormal scales)

Third, the transformation of leaves.

Bract: a deformed leaf born under a flower.

2. Scaled leaves: (fleshy) onion, lily, (membranous) water chestnut and arrowhead.

3. Leaf tendrils: peas

4. Insect catching leaves: pitcher plants and sundew.

5, leaflike stalk: Acacia formosana

6. Leaf thorn: Robinia pseudoacacia (thorn is located in stipules)

Four, homologous organs and organs with the same function

1. Homologous organs: organs from the same source have different physiological functions for a long time to adapt to different external environments, resulting in different functions and different shapes. Such as leaf thorns, scales, insect-catching leaves, leaf tendrils, etc.

2. Organs with the same function: Organs from different sources perform the same physiological function for a long time to adapt to a certain external environment, resulting in the same function and similar morphology. Such as stem vines and leaf vines, stem thorns and leaf thorns.

Section 6 Reproductive Organs (Flowers)

First, the reproduction of plants.

1, the concept of reproduction: plants grow to a certain stage and produce new individuals from themselves to continue their offspring in some way, which is reproduction.

2. Breeding mode:

1) asexual reproduction: the process of combining germ cells without using them. Mainly refers to vegetative reproduction.

The application of asexual propagation includes rooting, cutting, layering and grafting.

2) Sexual reproduction: it is a progressive reproductive form through the fusion of bisexual germ cells.

Second, the concept of flowers

Flowers are unbranched abnormal short branches, which are used to form megaspores, microspores and male and female gametes during sexual reproduction, and further develop into seeds and fruits.

Third, economic utilization.

1, spices: jasmine, white orchid, etc.

2, medicine: safflower, honeysuckle, chrysanthemum and so on.

3. Dye: Impatiens

Fourth, the composition of flowers.

A complete flower can be divided into five parts: pedicel, receptacle, perianth, stamen group and pistil group.

Verb (abbreviation of verb) the evolution of flowers

1, the number ranges from many but not fixed to few but fixed.

2. Symmetry ranges from radial symmetry (regular flowers) to bilateral symmetry (irregular flowers)

3. The change of ovary position: the original receptacle is conical or cylindrical. In the process of evolution, the receptacle gradually became shorter, its width increased and flattened, and the center was further depressed. The position of the ovary appears the following different types.

1) each part is inserted around the receptacle, and the pistil is higher than other parts, which is called the upper ovary and is the lower flower.

2) Recessed in the center of the receptacle, the ovary of the pistil is inserted at the bottom of the receptacle, and the bottom of the receptacle is not connected with the ovary wall, which is called the upper position of the ovary and is the central flower.

3) Recessed into the center of the receptacle, the pistil ovary is placed at the bottom of the receptacle, and the ovary wall and receptacle are completely healed, leaving only the style and stigma protruding from the receptacle. This kind of flower has the lowest ovary position, which is called the inferior ovary and is the superior flower.

Six, flower plan and flower schema

In order to simply explain the structure of a flower, the composition, arrangement and relationship of each part, we can use a formula or pattern to represent each part of a flower. The former is called the flower program, and the latter is called the flower schema.

Seven. flower

Some flowers of angiosperms are born alone in the top of branches or axils of leaves, which are called single-top flowers, such as magnolia, peony, lotus and peach blossom. But the flowers of most plants are inserted on the total flower stalk in a certain arrangement order, which is called inflorescence.

Inflorescences are mainly divided into two categories, one is infinite inflorescence and the other is limited inflorescence.

Viii. Flowering, pollination and fertilization

1. Flowering: When the pollen in the pistil and the embryo sac in the pistil reach the mature stage, or when one of them has matured, the flowers tightly wrapped by the perianth will open, exposing the pistil and pistil to prepare for the next pollination.

2. Pollination: The mature pollen scattered from the pollen sac is transferred to the pistil stigma of the same flower and another flower with the help of certain media.

3. Fertilization: After pollination, pollen germinates on the stigma into a pollen tube, and sperm is produced in the tube. After the pollen tube is elongated, it reaches the embryo sac and fuses with the egg cell and polar nucleus. The fertilized ovule further develops into a seed.

The phenomenon of double fertilization in angiosperms: after two sperm in the pollen tube are released into the embryo sac, one of them combines with the egg cell to form a fertilized egg and later develops into an embryo. Another sperm fused with two polar nuclei and later developed into endosperm.

Section 7 Seeds and Fruits

Seeds are the unique organs of all seed plants. The gymnosperms in seed plants are naked after the ovule develops into seeds, because there is no coating outside the ovule; However, the ovule of angiosperms is enclosed in the ovary. After fertilization, the ovary develops as a result, and the ovule inside develops into a seed, so the seed is also wrapped by the fruit. Whether seeds are coated or not is one of the important differences between gymnosperms and angiosperms.

I. Functions and uses of fruits and seeds

Function: (seed) 1) Increase the number of individuals of this species through reproduction.

2) Crossing harsh environments such as drought and cold.

(Fruit) 1) Protect seeds

2) store nutrients

3) auxiliary sowing seeds

2, uses: 1) grain 2) industrial raw materials (starch, protein, oil) 3) medicine.

Second, seeds.

1, seed structure: including embryo, endosperm and seed coat.

2. Embryo development: (Dicotyledonous plants)

3. Endosperm development: fertilization polar nucleus, multiple endosperm nuclei, multiple endosperm cells and endosperm tissues.

Third, the types of fruits.

1, true fruit: the pericarp develops from the ovary wall, as most plants do.

False fruit: In addition to the ovary, there are other parts involved in fruit composition, such as apples, melons and pears.

2, single fruit: a flower has only one pistil, and only one fruit will be formed in the future.

Aggregate fruit: Many small fruits formed by pistils gather on the same receptacle. Such as lotus and strawberry.

Picking flowers and fruits: Fruits are developed from the whole inflorescence, and inflorescences also participate in the components of fruits, such as mulberries, pineapples, figs and so on.

3, meat and fruit:

Berry (1): More common. In addition to several layers of cells on the surface, the peel is generally soft, juicy and contains many seeds, such as grapes, tomatoes (placenta) and persimmons.

Drupe: A single pistil develops and contains a seed. Exocarp is extremely thin, mesocarp is a developed fleshy part. The cells of the endocarp lignify and become hard nuclei, which are wrapped around the seeds. Such as peaches, plums, plums and apricots.

3) Pear fruit: It is generally owned by plants with flowers under the ovary. The fruit is a kind of false fruit, which is made up of receptacle and carpel. The fleshy part outside is protoreceptacle, and the fleshy part inside is pericarp.

2. Dried fruit: the peel is dry, and the edible part is generally seeds.

1) Fruit cracking: When the fruit is ripe, the peel will crack by itself.

A. Pod: Ripped at both sides. Such as soybeans, peas and broad beans; Peanut, acacia, Gleditsia sinensis, etc. ; Alfalfa, Sophora japonica.

B. Follicle: one side splits after maturity. Illicium verum, Peony and Platanus acerifolia

C. Capsules: lily and poppy

D. Pod: Cruciferae (cabbage, cauliflower, green vegetables, radish, shepherd's purse)

2) Harvest: After the fruit is ripe, the peel will not crack by itself.

Achene: the fruit is small, the peel is hard, and the peel and seed coat are easy to separate. Such as compositae strawberry (sunflower, lettuce, dandelion).

B. nuts: the fruit is large, the skin is hard and lignified. Such as walnuts, chestnuts and hazelnuts (the prickly shell outside chestnuts is developed from the inflorescence involucre)

C. samara: the peel extends into wings, such as elm and Pterocarya stenoptera.

D. kiwi fruit: carrots and fennel

E. Utricle: Amaranthaceae

Caryophyll: pericarp and seed coat are closely combined and difficult to separate. The fruit is small and generally easy to be mistaken for seeds. Such as Gramineae, the edible part is endosperm.

4. Adaptation of fruits and seeds to transmission

1, suitable for wind power generation

1) Small and light.

2) It has a special structure.

Wool: cotton, willow, dandelion

Fruit wing: elm

2. Adaptation to water

Loose organization, light weight, floating on the water. Such as lotus and coconut.

3. Adapt to the spread of animals and humans

1) Barbs and mucus: Xanthium sibiricum

2) It is food for some animals;

4. Rely on the mechanical strength of the plant itself.