The very existence of man and all animals is dependent on plants. The dependance is not only for food, clothes and shelter but is also for medicines and other applied areas. No doubt, advancement of science and technology has given a number of synthetic replacement for plants and plant products, but plants still occupy an important position in man’s life. Utility of plants to mankind is discussed below under various headings.
(i) Food
Chlorophyll containing green plants harvest light energy and convert it to chemical energy. All animals including man depend on these plants for food. Cereals (rice, wheat, maize, millets, oats, barley, etc.), pulses (grams, peas, etc.), oil seeds (mustard, groundnut, etc.) are used by man as sources of carbohydrates, proteins and lipids. Green vegetables and fruits provide necessary minerals and vitamins.
(ii) Clothing
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During the early civilization, man used animal skin to cover his body. But in course of time, he recognized the importance of plant fibres like cotton and jute. Though synthetic fibres like polypropylene and nylon have dominated the modern age, cotton has not lost its utility.
(iii) Shelter
Bamboo was the first plant to be used for shelter. Soon, timber followed by fibres of jute, coconut, hemp, etc. that were used as supplementary tools to construct houses. Household articles like bags, nets, carpets, etc. were also made from fibres. With the advancement of civilization, cement and concrete became the raw materials for house-building and timber remained confined to making furniture, doors and windows. Indiscriminate use of timber by man led to reduction of forest and ultimately ecological imbalance. Presently, use of wood has drastically reduced. Unless man learns to make a judicious use of plants, cutting of wood should be discouraged. Judicious use of plants and plant products will always be beneficial to mankind.
(iv) Medicines
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Chinese were the first to use plants for treating diseases. Way back in 5000 B.C., there is mention of medicinal plants in Rigveda and Atharvaveda. Ayurveda, the most important contribution of Indians to the field of medicines. Indigenous drugs have been described in Charak Samhita and Sushruta Samhita. Importance of medicinal plants has also been highlighted by Greek philosophers like Aristotle and Theophrastus. Plants are the sources for most of Ayurvedic, Allopathic and Homeopathic drugs. Ayurveda is on the revival track and its popularity is increasing. Through ethnobotanical studies, man is now trying to unravel the secrets of traditional medicine.
(v) Food adjuncts
Besides plants that can be used directly as sources of food, a number of plants yield products that increase the taste and flavour. Ginger, turmeric, cloves, cinnamon, black pepper, cardamom, fenugreek, nutmeg and asafoetida are some food adjuncts that enhance taste, flavour and appetite.
(vi) Beverages
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Man has always wanted to refresh himself. Nonalcoholic beverages like tea and coffee and stimulants like betel, tobacco, opium, hemp, etc. have always been used by man to refresh him self. Fermented juice of barley (beer) and grapes (wine), spirit distilled from wine (brandy), spirit distilled from cereal grains (whisky) are some of the alcoholic beverages of plant origin used by man for intoxication. No doubt, some of the beverages, stimulants and alcoholic beverages have been proved quite harmful to human health. Thus, there is a need to use them judiciously.
(vii) Forest products
Man is dependant on forest in a number of ways. Tribal people depend on the forest for fuel till today. Gums, resins, tannin, dyes, rubber, cork, etc. are some important forest products used by man. These products are not only economically important but are also behind the creation of industries.
(viii) Man and applied fields of botany
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Applied areas of botany like agriculture, horticulture, silviculture, arboriculture, olericulture, floriculture have facilitated man to make a better use of plants and plant products. Greater production of food grains, timber, fibres, vegetables and flowers is made possible because of the techniques involved in the above described applied areas of botany. Pharmacognosy helps man to exploit the medicinal value of plants. Biotechnology is a modern, area of biology that helps in exploiting the industrial use of plants and microorganisms. Genetic engineering is a special branch of biotechnology, that facilitates scientists to manipulate DNA for the best use of the organisms for mankind.
(ix) Plants and aesthetic value
Not only plants meet the basic needs of man, they also give aesthetic satisfaction through vegetation, gardens and flowers. The aesthetic importance of plants can never be quantified in terms of money.
(x) Botany and employment scope
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Studying botany opens up ample employment scope. It is a part of curriculum for students opting for study of medicine, pharmacy and forestry. Applied fields like agriculture, horticulture, biotechnology are offshoots of botany as one of the subjects of study. Botany has now become interdisciplinary.
(xi) Human survival
Presence of oxygen is responsible for sustenance of life. Plants being autotrophic take in carbon dioxide and release oxygen as byproduct. Liberation of oxygen from plants is responsible for the maintenance of life on earth. Man is one such living organisms along with other, sustained by plant.
It is a known fact that as non-disposal of dead bodies would result in piling up of dead organisms, leaving no place to live. Microorganisms (bacteria) are vital in decomposing all living organisms immediately after their death and releasing the elements back to the surroundings.