Aerial stems

3. Aerial stems – Some aerial parts of plants possess several buds, sufficient water and stored food. These parts can form new plants when detached and planted. Sugarcane is propagated from the stem portions. A piece of stem containing one or more nodes having buds is cut and planted in the soil. Soon the buds sprout and for aerial shoots and adventitious roots.
4. Bulbils – These are the specialized fleshy buds. Bulbils form new plants when they fall on ground. These bulbils arise in the axils of leaves in lily and dioscorea bulbifera. In Garlic the bulbils are formed on the inflorescence axis and replace flowers. They occurs over the swollen root in Oxalis and adjacent the fruit in Pineapple
5. Leaves – Some leaves produce adventitious buds, e.g., Begonia, Bryophyllum, Walking fern, etc. Begonia can give rise to adventitious buds on the lamina veins and petiole. When its leaf is injured and placed in the soil, new plants are formed by adventitious buds. In Bryophyllum the adventitious buds are borne on a suitable soil, many of the buds sprout and form new plants. In walking fern (Adiantum caudatum), the tips of the leaces can produce buds on touching the soil. These buds grow and form new plants.
Artificial vegetative reproduction
Vegetative reproduction is a type of artificial method of reproduction. These are common in many horticulture plants. These are useful for
a) Quick production of new plants,
b) Quick formation of seeds and fruit, and
c) Combining the good qualities of two varities.
The common methods used for artificial vegetative propagation are
I. Cutting
II. Layering
III. Gootee
IV. Grafting
V. Approach grafting
VI. Budding
VII. Tissue culture

1. Cutting – Cutting is a very common method of vegetative propagation of a desired variety. A cutting is a pieces of stem, root or leaf which has or can form one or more buds. Roots cutting is done in case of blackberry and raspberry.
Generally stem cutting is very common in horticultural plants. Stem is taken from a one-year old shoot and cut below one of the nodes and is of 20-30 cm in length. The lower part of the cutting (towards the former root) is defoliated and placed vertically in the soil. After some days the lower end of cutting produces adventitious roots and becomes an independent plant. The usual time of the planting of cutting is the spring. The success of the cutting depends upon its capacity to form adventitious roots.
Now-a-days, special growth hormones like IAA, IBA, NAA and terpenoids are applied in very dilute quantities to the lower end of the stem cutting. Their applications quicken the formation of adventitious roots. Stem cutting are done in Roses, Sugarcane, Citrus, Bougaimvillea, etc.
2. Layering – It can be carried out in those plants which possess soft branches near the soil. A long basal leaf branch of the plant is selected for layering. Such a branch is known as layer. It is pegged down in the soil or in a pot. The horizontal pegged part is defoliated. It is then injured in the median or sub-apical region by giving one of the following types of cuts.
I. Tongueing – an oblique cut is made.
II. Ringing – a ring of bark is removed at a sufficient length.
III. Notching – a “V” shaped cut upto the half of the width.
Layering is carried out the propagation of Grapevine, Jasmine, Ipomoea, etc.
3. Gootee – It is a method very similar to layering and hence is also called air layering. It is carried out in those plants where the branches are hard e.g., Litchi, Orange, etc. Gootee is done early during rainy season.
A healthy somewhat woody shoot is selected. A 2-5 cm ring of bark is removed towards the base of the branches. Alternately a notch or longitudinal cut can be given. The injured part is covered over by grafting clay and then wrapped by a waterproof plastic or polythene bag. The grafting clay is made up to clay (2 parts), cowdung (1 part) and some finely cut hay. A small quantity of root hormone (auxin) may also be added. It is then made into paste in water. After 1-3 months the root will appear at the injured region. Branch is now cut below the bandage and planted soil.

Organic compound

They are of several types – carbohydrates, lipids, proteins, enzymes, hormones, vitamins and nucleotides.

Carbohydrates – They are commonly called fuel compounds since respiration usually involves their oxidation of energy. Carbohydrates constitute 1-2% of the protoplasm. They are compounds of carbon, hydrogen and oxygen where hydrogen and oxygen occurs in the ration 1:2. Structurally carbohydrates are of three types – monosaccharides, oligosaccharides and polysaccharides.

Monosaccharides are simples sugar which cannot be further hydrolysed. The general formula is Cn H2n On. Depending upon the number of carbon atoms, monosaccharides are called dioses (C2H4O2), trioses, tetroses, pentoses, hexoses and heptoses. The two important pentose sugars are ribose and deoxyribose. They are constituents of RNA and DNA respectively. Amount hexoses glucose and fructose are used as respiratory substances. Most monosaccharides are sweet to taste. They readily dissolved in water and pass through cell membranes.

Oligosaccharides are condensation products of 2-6 monosaccharides. They are generally sweet and soluble. The most common disaccharide is sucrose or cane sugar. Others are maltose and lactose.

Raffinose is trisaccharide while stachyose is a tetrasaccharide. Oligosaccharides are generally employed for translocation of carbohydrates and sometimes for their storage (e.g., in sugarcane). Like monosaccharides, oligosaccharides are generally sweetish in taste. They dissolved in water but pass through cell membrances only slowly.

Polysaccharides are condensation products of a large number of monosachharides. They are of further two types – homopolysaccharides and heteropolysaccharides. Homoplysaccharides are made of a single types of monosaccharides e.g., starch, glycogen, cellulose, aranban, xylans, arabino-galactans (all found in hemicelluloses). Polysaccharides are not sweet in taste. They are not soluble in water. However, many of them form colloidal solutions. They are usually unable to pass through cell membrances.

Glucose a monosaccharides is the main substrate for liberation of energy during respiration. Therefore, it is also called respiratory fuel. Other hexose monosaccharides also de likewise. Pentose sugar ribose and deoxyribose are constituents of nucleic acids, nucleosides, nucleotides ATP, AMP, NAD, NADP, etc. Many monosaccharides (e.g., erythrorse, ribulose, xylulose, glyceraldehydes) from important intermediates of metabolic pathways. Some disaccharides (e.g., sucrose in sugarcane) and other oliogosachharides may be storage products in some plants. monosaccharides and oligosaccharides takes part in translocation of carbohydrates from one part to another part. Sugar derivatives (e.g., glucuronic acid, galacturonic acids, acetyl glucosamine) function as basic component of some important biochemical like pectic compounds, fungus cellulose, chitin, etc. Polysaccharides like starch (in plants) and glycogen (animals, fungi, bacteria) are the major storage materials. Some of the polysaccharides like cellulose in plants, chitin in arthropodas, and fungus cellulose in fungi function as supporting frame work. Oligosaccharides attached to constituents of cell membrances function in recognition. Hemicelluloses of plants cell walls binds cellulose with pectic compounds. Pectic compounds gives rise to mucilage or mucous for protection.

Role of essential elements

Carbon, Hydrogen and Oxygen – They are not minerals in origin. The elements are absorbed in the form of carbon dioxide and water. The three elements enter the composition of all types of organic compounds like carbohydrates, organic acids, amino acids, proteins, fats, enzymes, hormones, etc. In short they build up both the plants body as protoplasm.

Nitrogen – It is a constituent of amino acids, amides, proteins, enzymes, nucleic acid, and chlorophyll and alkaloids. As such it is essential for cell division full vegetative and reproductive growth, metabolism activities, photosynthesis, etc.

Phosphorus – It is a component of nucleic acids, phospholipids, some proteins, ATP, NAD, NADP, and some coenzymes. Being constitution of ATP, NAD and NADP, phosphorus takes part in energy transfer reactions. Phospholipids arc important constituent of cell membrance which control permeability. Hence it is required for the propthier metabolism, growth and development.

Sulphur – It is constituent of three amino acids (cysteine, cystine, and methionine), some B-vitamins (thiamine, biotin) and coenzymes. It is essential for synthesis of some proteins, enzymes, chlorophyll and nodule formation in legumes.

Potassium – Its intake a expulsion helps in the movement of stomata and other plants parts. Potassium maintains hydration turgidity and permeability of cells. It is essential for the functioning of several enzymes which take part in respiration photosynthesis, phosphorylation and synthesis of proteins, nucleic acids, starch, chlorophyll.

Magnesium – It is a component of chlorophyll. Magnesium is essential for fat synthesis, carbohydrate metabolism, phosphate transfer and binding of ribosomes.

Calcium – calcium is component of component of pectate present in middle lamella. It is activator of several enzymes of fat metabolism, krebs cycle, carbohydrate transport amylase and chromosome formation. Calcium prevents toxicity of metallic ions and oxalic acids.

Iron – It is a constituent of cytochromcs, ferredoxin, nitrogenase and many other enzymes. Iron is essential for the synthesis of proteins. Development of chloroplasts and their pigments (chlorophyll, carotenoids). It takes part in electrons transfer in both photosynthesis and respiration.

Manganese – It is an activator of several enzymes which take part in oxidation, reduction and de-carboxyiation. Manganese is also required for photolysis of water and evolution of oxygen during photosynthesis.

Zinc – Zinc is component and specific activator of several enzymes. It is essential for evolution and utilization of carbon dioxide. Zinc is requited for synthesis of auxin, protein and RNA.

Boron – It is essential for transport of substance in phloem, synthesis of pectins, proteins and nucleic acids and formation of root nodules in legumes. Boron enhances water and calcium absorption.

Copper – It is a component of several enzymes which take part in oxidation, carboxylation and transfer of electrons from photosynthesis one to two (as plastocyanln)

Molybdenum – It is essential for nitrogen fixation, nitrate reduction, ascorbic acid synthesis and functioning of same dehydrogenases.

Chloride – It is essential for evolution of oxygen during photosynthesis.

Importance

Water is the dispersion medium of the organic world in which concepts of protoplasm are dispersed. Many chemical reations required water reaction (e.g. hydrolysis, photosynthesis) or produce water (e.g. condensation, respiration). It maintains the turgidity of cells and their organelles. Only turgid protoplast and their organelles are physiologically active. Turgor pressure developed in the cell due to entry of water is essential for growth. Elongation of the root and its penetration through the soil are dependent upon development of turgor pressure. Changes in the turgor or water content cause many types of plant movements, e.g., stomatal movements, opening and closing of flowers, dehiscences of some fruits, folding and unfolding of leaves or leaflets. It helps in germination of seeds. Water maintains the form and structure of soft organs like leaves and flowers by the development of turgor pressure. It is a medium of translocation of different substances (both inorganic and organic) inside the plant. It is also a medium for absorption of various substances from outside. Proteins, carbohydrates, nucleic acids and other biological substances are active only in their hydrated state. Water has a high thermal conductivity, transparency and acts as a temperature buffer. It helps in ionization of solutes because of its high dielectric constant. Water molecules show both cohesion as well as adhesion.

Minerals – They form 1-3% of the protoplasm. The important minerals salts are chlorides, sulphates, phosphates, carbonates, bicarbonates, etc of sodium potassium, magnesium, iron, calcium, etc.

Many minerals present in the soil can enter the body of organisms but all of them are not essential. The essential elements for plants are sixteen in number. Some of them are exclusively present in organic or inorganic compounds, others occur in both. Depending upon their percentage, the essential elements are divisible into two categories:

1. Macronutrients (macro-elements or major elements) – C N H P K S Mg Ca
2. Micronutrients ( micro-elements or minor elements) – Fe B Mn Cu Zn Mo Cl. Iron (Fe) was formerly included under macronutrients but its concentration range lies below them. In animals, additional essential elements are sodium (Na), iodide (I), cobalt (Co) and fluorine (F).

In general, macronutrients build up the plants body (frame-work elements) and various cell constituents (protoplasmic elements) while micronutrients or minor elements are either integral part of electron carrier, enzymes or function as their confactors.

Living system Physical and chemical (Oxygen & Carbon)

A living system is made up of organs, organs of tissues, and tissues of cells. A cell contains protoplasm. Protoplasm is the name of living matter. All the biological properties of living beings like growth, metabolism, irritability, reproduction, etc. are basically the properties of protoplasm. Therefore, protoplasm has been called the physical basis of life by Huxley (1868).

Physico-Chemical Concept of Life. Before the beginning of modern era in physical sciences, life was considered to be something mysterious which was governed by its own special laws of vital forces, that could not be resolved into simpler physical and chemical principles. This is called vitalistie concept of life. However, in the nineteenth century the substances constituting the living matter were studied. It was found that all organic matter had its origin in the inorganic matter and life processes were governed not by vital forces but by discrete and simple physical and chemical principles. It is known as physic-chemical (or mechanistic) concept of life. It considers that life is simply an external manifestation of a large number of physical and chemical reactions. Further, the life in its vast diversity and complexity is derived by blending and interactions of a limited number of elements.

There is no well studied process of life which cannot be explained in terms of physical and chemical principles. Thus absorption, translocation and utilization of water and minerals salts, movements, phenomena of respiration and photosynthesis, formation of different types of organic substances, cell division, growth and differentiation of cells tissues or organs, transfer of hereditary characters, control of metabolic activities, development of variations, adaptations, adaptations, etc can all be explained on the basis of physical and chemical reactions.
Chemically a living system is made up of both inorganic and organic compounds.

Inorganic compounds
They are represented by water, salts and gases.
Gases. They include oxygen, carbon dioxide and some inert gases (e.g. nitrogen) Oxygen is obtained from the atmosphere. It is utilized in respiration. Carbon dioxide is evolved in respiration. It is a waste product and is expelled from the body.

Water. It contained 60-95% of a living system and 80-95% of the protoplasm. A molecule of water has two atoms of hydrogen connected to an atom of oxygen by covalent bonds.

Oxygen atom attracts electrons to a great extent than do hydrogen atoms. Therefore, oxygen end of water molecules has a slight negative charge while hydrogen ends show a slight positive charge. The two different charges help water molecules to form three-dimensional aggregates. The bonds formed among the water molecules are called hydrogen bond. Because of the presence of hydrogen bonds amongst water molecules, water a high specific heat, cohesion force and ability to stick to walls or adhesion force. The two different types of charges also allow water molecules to form shells around ions and charged ends of non-electrolytes. In this way water helps to disperse ions and molecules. Water molecules can also dissociate to form ions, H? (or H3O?) and OH’.

Field of Botany or Botanical Science (Plants) (logos)

Botany has several branches which deal with the different aspects of plants. They are called botanical sciences. Some of the more important botanical sciences are given below:
1. Morphology (Gk. Morphe-form, logos-study). Plants morphology or phytomorphology is the study of form and structure of plants. It is divided into two branches:
a) External Morphology. It deals with the external form, structure and relative position of plants organs. Some authors consider it as equivalent to morphology.

b) Internal Morphology. The study of internal structure of plants is called internal morphology. It is further divided into the following sub-branches:

(i) Anatomy (Gk. Ana-up, tome-cutting). It is the study of internal structure which can be seen with the naked eye after dissection. In plants, however, the unaided or naked eye cannot see much of the internal structure. Therefore, anatomy is generally regarded as equivalent to histology.

(ii) Histology (Gk. histos-tissues, logos-study). It is the study of tissue or details or internal structure by means of microscope. As remarked earlier, it is commonly thought to be equivalent to anatomy.

(iii) Cytology (Gk. Kytos-cells, logos-study). The study of form, structure and functions of cells, including the behavior of nucleus and other organelles, is called cytology.

2. Physiology (Gk. Physis-nature or functioning, logos-study). Physiology is the study of all types of body pathology.

3. Embryology (Gk. Embryo-embryo, logos-study). The study of early development of plants from fertilized eggs is known as embryology.

4. Plants Pathology (Gk. Pathos-suffering, logos-study; phyto-pathology). The study of various plants diseases (including diagnosis, causes, prevention and cure) is called plants pathology.

5. Plants Ecology (Gk. Oikos-place of living, logos-study). It is the study of reciprocal influence of external conditions or environment over the plants and adaptations shown by the plants to adjust themselves according to that environment.

6. Taxonomy or systematic Botany (Gk. taxis-arrangement, nomos-law). It is the study of identification, naming and classification or arrangement to the plants into group.

7. Economic or Applied Botany. It deals with the study of those plants which have some economic importance to human beings. The remaining branches of botany are collectively called pure botany. Economic botany has many sub-branches:

(a) Forestry. It includes the study of forest trees, silviculture (cultivation of forest trees), forest management and forest products.

(b) Horticulture. This branch includes the study of garden and orchards plants.
(c) Floriculture. It is the study of plants grown for their flowers.
(d) Agriculture. It is the science of farming or cultivating land for raising crop plants. Agriculture includes (raising and managing field crops), olericulture (raising and managing vegetables), soil management, crop improvement and protection of crops against posts, etc.

(e) Pharmacognosy. It is the branch of botany connected with the knowledge and use of medicine plants.

(f) Plants Breeding. It is the branch which takes care of raising plants for higher yield and better quality.

8. Palaeobotany (Gk. Palaios-ancient, botane-plants). It deals with study of plants fossils or remains of past plants found in the rocks of different ages.

9. Plants Geography. It is the study of distribution of plants in the different parts of the earth.

10. Genetics. It is the science which deals with variations and inheritance of characters from parents to their offspring.

11. Organic Evolution (L. e-out, volva-roll= to unroll). It deals with the origin of newer types of organisms from the previous types by modifications.

12. Some other Branches. According to the groups of plants, botany can be divided into

a. Algology (phycology) or the study of algae;
b. Mycology or the science of fungi;
c. Bacteriology or the study of bacteria;
d. Bryology or the study of bryophytes;
e. Pteridology or the science of pteridophytes;
f. Palynology or the study of pollen grains, etc.

IMPORTANCE OF PLANTS (BOTANY)

1. Evolution of Human civilization. Early man was essentially a hunter and fisherman. He started gathering edible parts of plants like roots, huts, berries, etc. seeds of the edible plants were thrown near human dwellings. Some of the seeds germinated. This gave the early man the idea of agriculture. With development of agriculture, man started living in communities. Thus arose the first civilization.

2. Fundamental Source of Food. All animals, including man, are dependent directly or indirectly on plants for their food supply. This is due to the reason that plants alone can manufacture organic food from inorganic raw materials by the process of photosynthesis. Human beings get a number of food materials directly from plants, e.g., cereals, pulses, vegetables, fruits, edible oils, sugar, etc.

3. Textiles. Cotton and line (from flax) form an important clothing material as more than 50% of clothes are made from them. Canvas, cordage, mats, gunny bags, etc. are obtained from Sann-hemp (vern-Sanai), jute and coconut (vern. Nariwal). The animal textiles like wool and silk indirectly come from plants because the animals textiles like wool and silk indirectly come from plants because the animals which produce them depends upon plants for their existence.

4. Shelter. In hills, far off island and earthquake areas, houses and entirely made up of wood. In other places wood is used in providing the necessary fitments in the modern building. The body of trucks and some other vehicles is also made of wood.

5. Fuel. Almost all sources of fuel (expect some source of electricity) come from the plants, i.e., fire-wood, coal, petroleum, etc. The latter two have been formed from the plants of the past under the influence of heat and pressure in the interior of the earth.

6. Disease. The majority of human, animal and plants disease are caused by bacteria and fungi, both of which are plants, e.g., tuberculosis, leprosy, cholera, ringworm, potato blight, etc. Such organisms are known as parasites. The diseases-producing parasitic are described as pathogens. The pathogens cause diseases either by eating away the host cells or producing poisonous substances.

7. Drugs. Substances which can cure diseases are called drugs. Only few a drugs are produced synthetically or obtained from sources other than plants. The various plants parts like roots, leaves, bark, fruits, seeds, etc. yield drugs. Some bacteria and fungi give antibiotic drugs which can cure several diseases caused by pathogens, e.g., penicillin, streptomycin, chloromycetin, terramycin.

8. Purification of Air. Oxygen is being constantly consumed and carbon dioxide added to the air due to respiration of organisms and burning of fuel. Excess of carbon dioxide is poisonous. It is taken up by the plants and changed into organic food in the process of photosynthesis. Oxygen is evolved as by-product. In this way, plants keep the percentage of carbon dioxide and oxygen constant in air. Water plants (e.g., Hydrilla, Ceratophyllum) are grown in aquaria for this purpose.

9. Trapping solar Energy. Solar radiations are a vest source of energy but we are unable to trap the same in a big way by any artificial method. Plants absorb a part of this solar energy and convert it into chemical energy which is stored in the organic compounds. The various life function of plants and other living beings and the working of many of our machines depend upon this chemical energy stored by the plants.

10. Scavengers. Some plants which cannot manufacture their own food get ready-made food from the dead bodies of other organisms. Such plants are saprophytes, e.g., many bacteria and fungi. The saprophytes break down the dead bodies of organisms. They cleanse the earth and create space for new generation of organisms. Thus they act like Nature’s scavengers.

11. Circulation of Raw Materials. The breakdown of organic matter by saprophytes releases the raw materials which can be re-used by green plants for the synthesis of new organic matter.

12. Minerals. At many places the deposits of silica, lime, iron, sulphur other minerals have been formed by metabolic activities of plants like diatoms, chara, bacteria, etc.

13. Soil Fertility. The saprophytic plants return raw materials to soil. Some bacteria and blue-green algae change the gaseous nitrogen into organic compounds. The process is called nitrogen fixation. There are others which destroy soil fertility by the process of denitrification, desulphurification, etc.

14. Soil Binders. The roots of the plants hold the soil particles firmly. Shoots of the plants protected the soil from direct action of rain and wind. Soil absorption also increases. Therefore, a good plant cover checks floods, prevent soil erosion and allows continuous supply of water.

15. Comfort. Plants are used for making many articles of daily use that provide comfort and enjoyment to human beings, e.g., furniture, walking sticks, playing articles, etc.

16. Other plants product. Many useful products are obtained from plants, e.g., paper, rubber, cork, resins, gums, perfumes, dyes, spices, beverages (tea, coffee, cocoa, wine, beer, etc), soaps, paints, etc. Several other useful products (e.g., perfumes, dyes, tar, fertilizers, etc.) are obtained from petroleum and coal, both of which are considered to be derived from plants of the past.

17. Profession. About fifty percent of the working population of the world is employed in industries and institutions connected with obtaining and processing useful plants products, e.g., agriculture, horticultures, floriculture, forestry, bakeries, oil industry, natural resin industry, rubber industry, tea, coffee and cocoa industries, textiles, sugar industry, paper industry, etc.

18. Research. A number of plants are employed for carrying research on various aspect like genetics (fungus Neurospora), cytology (alga Actabularia) and photosynthesis (alga Chlorella)

19. Aesthetic Value. Plants have received the admiration of young and old for their loving, enchanting and beautiful colours, the sweet pleasing and soothing scents and the landscapes they produce. They have stimulated the imagination of poets, artists and designers. It is because of their aesthetic value that the plants are grown to beautify our surrounding by growing grass lawns, flower beds, potted plants, veins and trees.