Botany वनस्पतिशास्त्र

Quick summary

Ecology is the study of the relationship between organisms and their environment. The growth and distribution of plants depend on many environmental factors. This topic covers the scope of plant ecology, the classification of ecological factors – climatic, edaphic, topographic and biotic – and their effects on plants, along with the laws of limiting factors and tolerance.

Key points

• The term ecology (oikos = house, logos = study) was coined by Ernst Haeckel (1869). Autecology studies a single species; synecology studies communities.
• Habitat – the place where an organism lives; ecological niche – its role and position in the community.
• Light – needed for photosynthesis; plants are heliophytes (sun plants) or sciophytes (shade plants); day length controls flowering (photoperiodism).
• Temperature – controls enzyme activity, germination, growth; plants are megatherms, mesotherms, microtherms, hekistotherms.
• Water – rainfall, humidity, dew; decides hydrophytes, mesophytes and xerophytes.
• Wind – causes dwarfing, deformed trees, transpiration loss; helps pollination and dispersal.
• Climatic factors:
• Soil formation from rocks by weathering; soil profile with horizons O, A, B, C and R.
• Soil texture – sand, silt, clay; loam is best for most crops.
• Soil water: gravitational, capillary water (available to plants), hygroscopic.
• Soil pH, soil air, organic matter (humus) and soil organisms (earthworms, microbes).
• Edaphic factors (soil):
• Topographic (physiographic) factors: altitude, slope, aspect (direction of slope) and height of mountain chains. With rising altitude, temperature falls, and vegetation changes much as it does with latitude.
• Biotic factors: effects of plants, animals and humans – grazing, trampling, deforestation, pollination, competition, parasitism, symbiosis (mycorrhiza, root nodules), epiphytism.
• Liebig's law of the minimum (1840): growth is controlled by the nutrient present in the least amount.
• Blackman's law of limiting factors (1905): when a process depends on several factors, its rate is limited by the factor present in the least favourable amount.
• Shelford's law of tolerance (1913): every organism has a minimum, optimum and maximum for each factor; stenotypic species have narrow and eurytypic wide tolerance.

Important terms

• Edaphic factor – a soil-related factor affecting plants.
• Humus – dark, decomposed organic matter in soil.
• Soil profile – vertical section showing soil layers (horizons).
• Heliophyte / sciophyte – plant adapted to bright light / shade.
• Limiting factor – the factor that controls the rate of a process when in short supply.

Key facts

5 important questions

Q1. Define ecological niche.

An ecological niche is the functional role of a species in its community – what it eats, where it lives, when it is active and how it interacts with other species and the environment.

Q2. State Shelford's law of tolerance.

Each organism can survive only within a range of each environmental factor, between a minimum and a maximum, with the best growth at the optimum. Its distribution is controlled by the factor for which its tolerance is narrowest.

Q3. Describe climatic factors and their effects on vegetation.

Light (intensity, quality, duration), temperature, water, wind – effects and plant adaptations with examples.

Q4. Explain edaphic factors.

Soil formation, profile, texture, soil water types, soil air, pH, organic matter, soil organisms; importance for plant growth; diagram of soil profile.

Q5. Write notes on topographic and biotic factors.

Altitude, slope and aspect; biotic effects of animals, humans, microbes; positive and negative interactions.

Exam tip

Always draw the soil profile diagram for edaphic factors. Remember three laws with years: Liebig 1840, Blackman 1905, Shelford 1913.

Quick summary

An ecosystem is a functional unit of nature where living organisms interact with each other and with their physical environment. The term was coined by A. G. Tansley (1935). This topic covers components of an ecosystem, food chains and food webs, ecological pyramids, energy flow, productivity, biogeochemical cycles and ecological succession.

Key points

• Ecosystem (परिसंस्था) = biotic (living) + abiotic (non-living) components working together.
• Abiotic components: light, temperature, water, soil, air, minerals.
• Biotic components: producers (green plants), consumers (herbivores – primary; carnivores – secondary and tertiary) and decomposers (bacteria and fungi).
• Types: natural (forest, grassland, pond, desert, ocean) and artificial (crop field, garden, aquarium).
• Food chain – a series of organisms through which food energy passes: grass → grasshopper → frog → snake → eagle.
• Grazing food chain starts with green plants; detritus food chain starts with dead organic matter.
• Food web – interconnected food chains; it makes an ecosystem stable.
• Energy flow is unidirectional (sun → producers → consumers) and follows the laws of thermodynamics.
• Lindeman's 10% law (1942): only about 10% of energy at one trophic level passes to the next.
• Ecological pyramids (Charles Elton): pyramid of number, biomass and energy. The pyramid of energy is always upright. The pyramid of biomass in a pond (sea) is inverted; the pyramid of number in a tree ecosystem is inverted (spindle).
• Biogeochemical cycles recycle nutrients: carbon, nitrogen, phosphorus (sedimentary), water.
• Ecological succession: gradual, orderly change in a community until a stable climax community forms. Primary succession starts on bare areas (rocks – xerosere; water – hydrosere); pioneer species on rock are lichens.

Important terms

• Trophic level – feeding position in a food chain.
• Gross primary productivity (GPP) – total rate of organic matter produced by photosynthesis.
• Net primary productivity (NPP) – GPP minus respiration loss of producers.
• Standing crop – amount of living matter present at a given time.
• Ecotone – transition zone between two ecosystems.
• Ecological niche – the functional role and position of a species in its habitat.
• Seral stages (seres) – series of transitional communities in succession.

Formulas

• NPP = GPP − R (R = respiration of producers).
• 10% law example: if producers fix 10,000 J, primary consumers get about 1,000 J, secondary consumers about 100 J and tertiary consumers about 10 J.
• Ecological efficiency (%) = (energy at higher trophic level ÷ energy at lower trophic level) × 100.

5 important questions

Q1. Why is the pyramid of energy always upright?

Energy decreases at every higher trophic level because much is lost as heat during respiration and other activities. So the higher level always has less energy, and the pyramid can never be inverted.

Q2. If GPP of a grassland is 20,000 kcal/m²/year and respiration of producers is 8,000 kcal/m²/year, find NPP.

NPP = GPP − R = 20,000 − 8,000 = 12,000 kcal/m²/year. This is the energy available to herbivores.

Q3. Describe the structure and function of a pond ecosystem.

• Abiotic: water, dissolved gases, minerals, light, temperature.
• Producers: phytoplankton (algae), floating and rooted plants (Hydrilla, Vallisneria, water lily).
• Consumers: zooplankton, insects, fish, frogs, birds.
• Decomposers on the bottom.
• Zones: littoral, limnetic, profundal.
• Food chain example and energy flow.

Q4. Explain energy flow in an ecosystem.

• Sun is the source; producers trap about 1–2% of incident light (approx.).
• Flow is unidirectional; heat loss at each level.
• 10% law; long food chains are rare.
• Single-channel and Y-shaped energy flow models (Odum).
• Draw energy flow diagram with boxes and arrows showing loss as heat.

Q5. Describe hydrosere (succession in water).

• Phytoplankton stage → submerged plant stage (Hydrilla) → floating stage (Nymphaea, Pistia) → reed swamp (Typha, Phragmites) → sedge meadow → woodland → climax forest.
• Each stage changes the habitat (silt and organic matter build up, water becomes shallow).
• Ends in a stable climax community suited to the climate.

Exam tip

Draw the three ecological pyramids, including inverted examples. Remember Tansley (1935) and Lindeman (1942).

Quick summary

Plants do not grow alone; they live together in groups called plant communities. Ecologists describe communities by their composition, structure and life forms, and measure them in the field with quadrats and transects. This topic covers characters of a community, Raunkiaer's life forms, and quantitative analysis – frequency, density, abundance and the Importance Value Index – with a worked example.

Key points

• Plant community – an assemblage of plant populations living together in a common area and interacting with each other.
• Qualitative characters: floristic composition, physiognomy (general appearance), stratification (layering – trees, shrubs, herbs, ground layer), phenology (seasonal timing of leafing, flowering), sociability and life forms.
• Quantitative characters: frequency, density, abundance, cover/basal area.
• Synthetic characters: presence and constancy, dominance, fidelity, Importance Value Index (IVI).
• Dominant species controls the community and gives it its name (e.g. teak forest). Ecotone – transition zone between two communities, often rich in species (edge effect).
• Phanerophytes – buds high above ground (trees, shrubs); dominant in tropics.
• Chamaephytes – buds near ground surface (below 25 cm).
• Hemicryptophytes – buds at soil surface (grasses).
• Cryptophytes – buds below soil or water (bulbs, rhizomes).
• Therophytes – survive as seeds (annuals); common in deserts.
• Raunkiaer's life forms (1934) – based on the position of perennating buds:
• The percentage of each life form in a flora is its biological spectrum; it reflects the climate.
• Quadrat method – square sample plots (1 m × 1 m for herbs, 5 m × 5 m for shrubs, 10 m × 10 m or more for trees) placed at random. Minimum quadrat size is found from a species–area curve.
• Line transect / belt transect – used where vegetation changes along a gradient.
• Raunkiaer's frequency classes: A (1–20%), B (21–40%), C (41–60%), D (61–80%), E (81–100%); normal law A > B > C ≥ D < E.

Important terms

• Physiognomy – overall look of vegetation.
• Stratification – vertical layering of a community.
• Quadrat – sample plot of known size.
• Ecotone – transition zone between two communities.
• Biological spectrum – percentage distribution of life forms in a flora.

Formulas

• Frequency (%) = (Number of quadrats in which the species occurs ÷ Total quadrats studied) × 100
• Density = Total individuals of the species ÷ Total quadrats studied
• Abundance = Total individuals of the species ÷ Number of quadrats in which it occurs
• IVI = Relative frequency + Relative density + Relative dominance (maximum 300)

5 important questions

Q1. What is an ecotone?

An ecotone is the transition zone between two different communities, such as forest and grassland. It often has more species than either community, which is called the edge effect.

Q2. Name Raunkiaer's five life forms.

Phanerophytes, chamaephytes, hemicryptophytes, cryptophytes and therophytes.

Q3. In 10 quadrats, species X was found in 6 quadrats with 30 individuals in all. Find frequency, density and abundance.

1. Frequency = (6 ÷ 10) × 100 = 60% (Raunkiaer class C).
2. Density = 30 ÷ 10 = 3 individuals per quadrat.
3. Abundance = 30 ÷ 6 = 5 individuals per quadrat of occurrence.

Q4. Describe the characters of a plant community.

Qualitative (composition, physiognomy, stratification, phenology, life forms), quantitative (frequency, density, abundance, cover) and synthetic (dominance, IVI) characters with examples.

Q5. Explain the quadrat method of vegetation study.

Choosing quadrat size (species–area curve), laying quadrats randomly, recording data, calculations of frequency, density, abundance; transect method for gradients.

Exam tip

Practise the three formulas – frequency, density and abundance – they appear as practical numericals every year. Keep units clear: density is per quadrat (or per m²).

Quick summary

Plants living in very wet, very dry or very salty places show special structural and physiological features called ecological adaptations. Based on water relations, plants are grouped as hydrophytes, mesophytes and xerophytes; plants of saline soils are halophytes. This topic covers their morphological, anatomical and physiological adaptations with examples.

Key points

• Hydrophytes – plants growing in water or very wet soil. Types: free-floating (Pistia, Eichhornia, Lemna, Wolffia), rooted with floating leaves (Nymphaea, Nelumbo), submerged (Hydrilla, Vallisneria), amphibious (Sagittaria, Ranunculus) and emergent (Typha).
• Roots poorly developed or absent; root pockets in place of root caps (Eichhornia, Pistia).
• Stems and petioles spongy; aerenchyma gives buoyancy and stores air (petiole of Eichhornia swollen).
• Submerged leaves thin, ribbon-like or finely dissected; heterophylly in amphibious plants.
• Thin or no cuticle; epidermis takes in gases and minerals; stomata absent in submerged leaves and on the upper surface only in floating leaves.
• Vascular tissue (especially xylem) and mechanical tissue reduced.
• Hydrophyte adaptations:
• Xerophytes – plants of dry habitats (deserts, rocky soils). Types: ephemerals (drought escapers – short life cycle in rainy season), succulents (drought avoiders – store water: Opuntia, Aloe, Euphorbia), non-succulents (drought endurers – Calotropis, Nerium, Casuarina, Acacia).
• Very long tap roots; extensive root system.
• Leaves reduced, modified into spines (Opuntia), scales (Casuarina); phylloclades do photosynthesis.
• Thick cuticle, multiple epidermis (Nerium), sunken stomata in pits with hairs (Nerium).
• Leaf rolling (grasses like Ammophila with hinge/bulliform cells), hairy coverings.
• Well-developed sclerenchyma and xylem; water-storage tissue in succulents.
• CAM photosynthesis: stomata open at night (cacti, pineapple).
• Xerophyte adaptations:
• Halophytes – plants of saline soils, e.g. mangroves of coasts (Rhizophora, Avicennia, Sonneratia).
• Halophyte adaptations: pneumatophores (negatively geotropic breathing roots with lenticels), stilt roots for support, succulent leaves, salt glands that excrete salt, high osmotic pressure of cell sap, and vivipary (seed germinates on the parent tree, e.g. Rhizophora).
• Mesophytes grow in moderate conditions (most crops) and show intermediate features.

Important terms

• Aerenchyma – parenchyma with large air spaces.
• Heterophylly – different leaf forms on the same plant.
• Sunken stomata – stomata in pits below the epidermis, reducing water loss.
• Pneumatophore – breathing root of mangroves.
• Vivipary – germination of seeds while still attached to the parent.

Key facts

5 important questions

Q1. What is vivipary?

Vivipary is the germination of seeds while the fruit is still attached to the parent plant. It is seen in mangroves like Rhizophora; the seedling drops into the mud and fixes itself quickly.

Q2. What are sunken stomata? Give an example.

Stomata placed in pits (stomatal crypts) below the leaf surface, often covered with hairs, which reduce water loss. Example: Nerium leaf.

Q3. Describe the morphological and anatomical adaptations of hydrophytes.

Types with examples; root, stem and leaf adaptations; aerenchyma, reduced xylem, stomata; T.S. of Hydrilla stem.

Q4. Explain the adaptations of xerophytes.

Ephemerals, succulents, non-succulents; morphological, anatomical (Nerium leaf T.S.) and physiological (CAM, osmotic adjustment) adaptations.

Q5. Write a note on mangrove vegetation.

Habitat, examples, pneumatophores, stilt roots, vivipary, salt glands; importance in coastal protection (Sundarbans, Konkan coast).

Exam tip

In practicals, Nerium leaf T.S. (xerophyte) and Hydrilla stem T.S. (hydrophyte) are the standard slides. Write three clear anatomical features for each identification.

Quick summary

Phytogeography (plant geography) studies the distribution of plants on the Earth and the reasons for it. India, with its varied climate and landforms, has very rich vegetation. This topic covers the principles of plant distribution, endemism, the phytogeographical regions of India, the main forest types and the vegetation of Maharashtra.

Key points

• Phytogeography has two branches: descriptive (floristic) – where plants grow, and interpretive (ecological) – why they grow there.
• Factors controlling distribution: climate (temperature, rainfall), soil, topography, geological history (continental drift, glaciation) and dispersal barriers.
• Endemism – a species restricted to a particular area. India has many endemics, especially in the Western Ghats, Eastern Himalaya and Andaman–Nicobar Islands.
• Continuous distribution – species found over wide areas (cosmopolitan, e.g. Cynodon). Discontinuous distribution – species in widely separated areas.
• Phytogeographical regions of India – D. Chatterjee (1939; revised 1962) recognised 9 regions; Champion and Seth (1968) classified Indian forests into 16 major types.
• Common 9 regions (Chatterjee): Western Himalaya, Eastern Himalaya, Indus Plain, Gangetic Plain, Central India, Deccan, Western Ghats (Malabar), Assam, Andaman and Nicobar.
• Major forest types (Champion and Seth): tropical wet evergreen, tropical semi-evergreen, tropical moist deciduous (sal, teak), tropical dry deciduous (teak, tendu), tropical thorn, littoral and swamp (mangroves), subtropical, temperate, subalpine and alpine.
• Western Ghats – one of the world's biodiversity hotspots; wet evergreen forests with many endemic orchids and Impatiens species.
• Konkan coast – mangroves (Rhizophora, Avicennia) and semi-evergreen forests.
• Western Ghats (Sahyadri) – evergreen and semi-evergreen forests, Kaas plateau with seasonal flowers (UNESCO World Heritage with the Western Ghats).
• Deccan plateau – dry deciduous and thorn forests.
• Vidarbha (Nagpur, Bhandara, Gondia, Chandrapur) – tropical dry deciduous forests dominated by teak (Tectona grandis), with tendu, mahua, bamboo; protected areas like Tadoba-Andhari and Nagzira sanctuaries.
• Maharashtra vegetation:
• Other phytogeographic ideas: age and area hypothesis (Willis) – older species occupy larger areas; continental drift (Wegener) explains discontinuous distributions.

Important terms

• Endemic species – species found naturally only in one region.
• Biodiversity hotspot – region very rich in endemic species and under threat.
• Discontinuous distribution – occurrence of a taxon in widely separated areas.
• Flora – all plant species of a region.
• Vegetation – the plant cover of an area.

Key facts

5 important questions

Q1. What is endemism?

Endemism is the restriction of a species to a particular geographical area where it occurs naturally. Example: many orchids and balsams of the Western Ghats are endemic.

Q2. Name the dominant tree of the forests of Vidarbha.

Teak (Tectona grandis) dominates the tropical dry deciduous forests of Vidarbha, along with tendu, mahua and bamboo.

Q3. Describe the phytogeographical regions of India.

Name each region with climate and dominant vegetation (use the table), and draw a rough outline map.

Q4. Give an account of forest types of India.

Champion and Seth's classification; main groups with climate, distribution and examples.

Q5. Write a note on the vegetation of Maharashtra.

Konkan, Western Ghats, Deccan plateau and Vidarbha – forest types, examples, protected areas.

Exam tip

Learn the region names with one dominant plant each. A note on the vegetation of your own area (Vidarbha teak forests) adds local value in RTMNU exams.

Quick summary

A plant disease is any harmful change in the normal structure or function of a plant caused by a pathogen or by bad environmental conditions. Plant pathology studies the causes, symptoms, spread and control of plant diseases. This topic covers classification of diseases, common symptoms, the disease triangle, important Indian crop diseases and methods of control.

Key points

• Plant pathology (phytopathology) is the study of plant diseases. Disease is रोग in Marathi.
• Anton de Bary is called the father of plant pathology. In India, E. J. Butler is called the father of Indian plant pathology.
• Pathogens: fungi (most diseases), bacteria, viruses, viroids, phytoplasma (mycoplasma-like organisms), nematodes, and parasitic plants (Cuscuta, Striga).
• Non-parasitic diseases are caused by nutrient deficiency, pollution, frost, drought, etc.
• By spread: endemic (always present in a region), epidemic (sudden, widespread), sporadic (occasional), pandemic (over continents).
• Disease triangle: disease needs a susceptible host, a virulent pathogen and a favourable environment.
• Koch's postulates are used to prove that a particular organism causes a disease.
• Spread (dissemination): wind, water, insects (vectors), seeds, soil, tools and humans.
• Historic example: the Bengal famine of 1943 is linked to brown spot of rice (Helminthosporium oryzae, now Cochliobolus miyabeanus); the Irish famine (1845–1846) was due to late blight of potato (Phytophthora infestans).

Important terms

• Symptom – visible change caused by disease (e.g. spot, wilt, rot).
• Leaf spot – dead areas on leaves.
• Blight – sudden browning and death of leaves and shoots.
• Rust – reddish-brown powdery pustules (rust fungi).
• Smut – black powdery spore masses (smut fungi).
• Wilt – drooping due to blocked xylem or root damage.
• Mildew – white powdery or downy growth on leaves.
• Mosaic – patchy light and dark green colour (viruses).
• Canker – sunken dead lesion on stem, fruit or leaf.
• Damping off – death of young seedlings near soil level.

Key facts

• Control methods: cultural (crop rotation, removing infected plants, clean seed), chemical (fungicides like Bordeaux mixture – copper sulphate + lime; seed treatment), biological (Trichoderma, Pseudomonas fluorescens), resistant varieties, quarantine laws, and integrated disease management (IDM).

5 important questions

Q1. What is the disease triangle?

The disease triangle shows that a plant disease develops only when three factors meet: a susceptible host, a virulent pathogen and a favourable environment. If any one is absent, disease does not occur.

Q2. What is Bordeaux mixture?

Bordeaux mixture is a fungicide made by mixing copper sulphate and lime (calcium hydroxide) in water. It was discovered by Millardet (1882) in France while fighting downy mildew of grapes.

Q3. Describe late blight of potato.

• Pathogen: Phytophthora infestans.
• Symptoms: water-soaked spots on leaves that turn brown-black; white growth on lower side in humid weather; tubers rot.
• Favoured by cool, humid, cloudy weather.
• Spread: sporangia by wind and rain; infected seed tubers.
• Control: healthy seed, resistant varieties, fungicide sprays (e.g. mancozeb, Bordeaux), destroying infected plants.

Q4. Explain the methods of controlling plant diseases.

• Exclusion: quarantine, certified seed.
• Eradication: removing alternate hosts and infected plants; crop rotation.
• Protection: chemical fungicides and seed treatment.
• Biological control: antagonistic microbes.
• Host resistance: resistant varieties.
• IDM: combining these.

Q5. Describe red rot of sugarcane.

• Pathogen: Colletotrichum falcatum.
• Symptoms: drying of leaves; split stalk shows red patches with white cross bands; sour (alcoholic) smell.
• Spread: infected setts, soil, water.
• Control: healthy setts, hot-water/ fungicide treatment, resistant varieties, crop rotation.

Exam tip

Learn the pathogen name for each Indian crop disease; questions often ask "name the causal organism of…".

Quick summary

Economic botany studies plants that are useful to humans – for food, fibre, oil, medicine, timber, beverages, spices and more. India is rich in such plants. This topic covers cereals, pulses, oilseeds, fibres, sugar crops, beverages, spices, medicinal plants and timber, giving the botanical name, family and useful part of each.

Key points

• Economic botany links plant science with agriculture, industry and trade.
• Cereals belong to the grass family Poaceae (Gramineae); their grain is a caryopsis; they supply most of our carbohydrates.
• Pulses belong to Fabaceae (Leguminosae); their seeds are rich in protein; their root nodules fix nitrogen.
• Oilseeds give edible and industrial oils.
• Fibres are surface fibres (cotton), bast/stem fibres (jute, flax) or leaf fibres (sisal).
• Medicinal plants give drugs from roots, bark, leaves, seeds or latex.
• Spices and condiments add flavour and colour.

Important terms

• Caryopsis – one-seeded dry fruit where the seed coat is fused with the fruit wall (cereals).
• Bast fibre – fibre from phloem (secondary phloem) of stems.
• Retting – soaking stems in water so that microbes loosen the fibres (jute).
• Ginning – separating cotton fibres (lint) from seeds.
• Alkaloid – nitrogen-containing plant compound with strong action on the body (e.g. quinine, reserpine).

Key facts

• Maharashtra (especially Vidarbha) is a major cotton-growing region; Vidarbha also grows soybean, tur and oranges (Nagpur oranges).
• Bhandara and Gondia districts are known for paddy (rice) cultivation.

5 important questions

Q1. Give the botanical name, family and useful part of turmeric.

Turmeric is Curcuma longa of family Zingiberaceae. Its underground stem (rhizome) is used as a spice, a colouring agent and in medicine (curcumin).

Q2. What is retting?

Retting is the process of soaking harvested jute stems in slow-moving water for some days. Microbes decompose the soft tissues, so the bast fibres can be separated easily.

Q3. Write a note on cotton.

• Botanical name Gossypium spp. (G. hirsutum, G. arboreum, G. herbaceum); family Malvaceae.
• Fibres are epidermal hairs of the seed coat (lint); short fuzz is linters.
• Grown on black cotton soil (regur) – Maharashtra, Gujarat, Telangana.
• Processing: picking, ginning, baling, spinning.
• Uses: textiles; seed oil and oil cake (cattle feed).

Q4. Describe the economic importance of the family Fabaceae.

• Pulses: tur, gram, moong, urad, masoor – protein.
• Oilseeds: groundnut, soybean.
• Fodder: berseem, lucerne.
• Timber: shisham (Dalbergia sissoo).
• Soil fertility via Rhizobium nodules.
• Medicinal: liquorice (Glycyrrhiza glabra).

Q5. Name five medicinal plants with their uses.

• Rauvolfia serpentina – reserpine, high blood pressure.
• Cinchona – quinine, malaria.
• Azadirachta indica – antiseptic, insecticide.
• Withania somnifera – tonic.
• Aloe vera – skin care, burns.
• Ocimum – cough and cold.

Exam tip

Learn "botanical name – family – useful part" for at least two plants in each group. Write botanical names in italics or underline them.

Quick summary

Ethnobotany studies the relationship between people – especially tribal and rural communities – and plants: how they use plants for food, medicine, fibre, rituals and daily life. Medicinal plants contain active compounds used to treat diseases. This topic covers the scope and methods of ethnobotany, important tribes and ethnobotanical plants of Maharashtra, traditional systems of medicine, and important medicinal plants with their active principles.

Key points

• The term ethnobotany was coined by J. W. Harshberger (1895). In India, S. K. Jain is called the father of Indian ethnobotany.
• Branches: ethnomedicine, ethnoagriculture, ethnopharmacology, ethnoecology, ethnotaxonomy.
• Methods: field surveys with tribal healers (vaidus), interviews and questionnaires, herbarium specimens, study of old texts and folklore, market surveys, and laboratory testing of claims.
• Tribes of Maharashtra with rich plant knowledge: Gond and Madia (Gadchiroli, Chandrapur, Vidarbha), Korku (Melghat), Bhil, Warli and Katkari, Kolam.
• Ethnobotanical uses common in Vidarbha: mahua (Madhuca longifolia) flowers as food and liquor, seeds for oil; tendu (Diospyros melanoxylon) leaves for bidi; bamboo for houses and baskets; charoli (Buchanania lanzan) seeds; gum from Sterculia urens (karaya).
• Traditional systems of medicine: Ayurveda, Siddha, Unani, Homoeopathy, folk medicine (AYUSH). Ayurveda texts: Charaka Samhita, Sushruta Samhita.
• Active principles (secondary metabolites): alkaloids, glycosides, tannins, essential oils, resins, flavonoids, saponins.
• Pharmacognosy – study of crude drugs of natural origin (identification, quality, active compounds).
• Conservation concerns: overharvesting of roots and bark endangers species (e.g. Rauvolfia, Gloriosa, sarpagandha); cultivation and sustainable collection are needed.
• Intellectual property: traditional knowledge is recorded in India's Traditional Knowledge Digital Library (TKDL) to prevent biopiracy (neem and turmeric patent cases).

Important terms

• Ethnobotany – study of plant use by people of a particular culture or region.
• Crude drug – dried, unprocessed plant part used as medicine.
• Alkaloid – nitrogen-containing basic compound with strong physiological action.
• Glycoside – compound of a sugar with a non-sugar part (aglycone).
• Biopiracy – commercial use of biological resources or traditional knowledge without permission or benefit sharing.

Key facts

5 important questions

Q1. Who is the father of Indian ethnobotany?

Dr. S. K. Jain, who carried out extensive ethnobotanical surveys among tribal communities of India and established ethnobotany as a discipline in the country.

Q2. Name the active principle and use of Rauvolfia serpentina.

Its roots contain the alkaloid reserpine, which is used to lower high blood pressure and as a sedative.

Q3. Explain the scope and methods of ethnobotany.

Definition; branches; field methods (survey, interview, herbarium), literature and laboratory methods; importance in drug discovery and conservation.

Q4. Describe ethnobotanical uses of plants by tribes of Maharashtra.

Gond, Madia, Korku, Warli, Bhil; uses of mahua, tendu, bamboo, charoli, karaya gum; medicinal uses for wounds, fever, snake bite.

Q5. Write an account of any five medicinal plants.

For each: botanical name, family, part used, active principle and medicinal use (use the table).

Exam tip

Learn five medicinal plants in the format "name – family – part – principle – use". Local Vidarbha examples (mahua, tendu, Gond tribe) are valued in RTMNU answers.

Quick summary

Biodiversity is the variety of all living organisms on Earth at the level of genes, species and ecosystems. It gives us food, medicine, clean air and water, and keeps ecosystems stable. Today biodiversity is being lost very fast. This topic covers levels of biodiversity, its value, hotspots, threats, IUCN categories and methods of in-situ and ex-situ conservation, with Indian examples.

Key points

• The term biodiversity was made popular by E. O. Wilson (the word was first used by Walter G. Rosen, 1985). Biodiversity is जैवविविधता in Marathi.
• Levels: genetic diversity (variation within a species, e.g. many varieties of rice and mango in India), species diversity (number of species in an area), ecosystem diversity (forests, deserts, wetlands, coral reefs).
• India is one of the world's megadiverse countries, with about 2.4% of the world's land area but a much larger share of its species.
• Biodiversity hotspots (concept by Norman Myers, 1988): regions very rich in endemic species and under severe threat. Four hotspots include parts of India: Western Ghats and Sri Lanka, Himalaya, Indo-Burma, and Sundaland (Nicobar Islands).
• Threats (the "evil quartet"): habitat loss and fragmentation, over-exploitation, invasion of alien species (e.g. Parthenium, Lantana, water hyacinth Eichhornia), and co-extinctions. Also pollution and climate change.
• IUCN Red List categories: Extinct, Extinct in the Wild, Critically Endangered, Endangered, Vulnerable, Near Threatened, Least Concern (and Data Deficient, Not Evaluated).
• In-situ conservation (on-site): national parks, wildlife sanctuaries, biosphere reserves, sacred groves.
• Ex-situ conservation (off-site): botanical gardens, zoos, seed banks, gene banks, cryopreservation, tissue culture.
• Convention on Biological Diversity was signed at the Earth Summit, Rio de Janeiro, 1992.
• India passed the Biological Diversity Act, 2002, and set up the National Biodiversity Authority (Chennai).

Important terms

• Endemic species – found only in a particular region.
• Biosphere reserve – large protected area with a core zone (no disturbance), buffer zone (limited activity) and transition zone (human settlements). India's first was Nilgiri (1986).
• Sacred groves – forest patches protected by local communities for religious reasons (called devrai in Maharashtra).
• Seed bank – store of seeds kept at low temperature and humidity.
• Cryopreservation – storage of cells, tissues or seeds in liquid nitrogen at −196 °C.
• Bioprospecting – searching for useful products (drugs, genes) from living organisms.

Key facts

• Protected areas in Maharashtra and Vidarbha: Tadoba–Andhari Tiger Reserve (Chandrapur), Pench Tiger Reserve (Nagpur), Melghat Tiger Reserve (Amravati), Navegaon–Nagzira Tiger Reserve (Gondia–Bhandara), Sanjay Gandhi National Park (Mumbai).
• India's important in-situ programmes: Project Tiger (1973), Project Elephant (1992).
• Ex-situ examples: National Bureau of Plant Genetic Resources (NBPGR) gene bank, New Delhi; botanical gardens such as the Indian Botanic Garden, Howrah.
• Values of biodiversity: direct (food, fuel, fibre, medicine, timber), indirect (pollination, soil formation, climate regulation, water cycle), aesthetic, ethical and cultural.

5 important questions

Q1. What is a biodiversity hotspot?

A hotspot is a region that has a very high number of endemic species and has already lost much of its natural habitat. The concept was given by Norman Myers. The Western Ghats is an example in India.

Q2. What are sacred groves?

Sacred groves are patches of forest protected by local people because of religious beliefs. Cutting trees there is not allowed, so they preserve many rare plants. In Maharashtra they are called devrai.

Q3. Explain the levels of biodiversity.

• Genetic diversity: differences in genes within a species; e.g. varieties of rice and mango; helps adaptation.
• Species diversity: number and abundance of species; e.g. Western Ghats amphibians.
• Ecosystem diversity: variety of habitats and communities; e.g. deserts, forests, mangroves, wetlands in India.
• All three levels are linked.

Q4. Describe the causes of loss of biodiversity.

• Habitat loss and fragmentation (deforestation, mining, cities).
• Over-exploitation (over-hunting, over-collection of medicinal plants).
• Alien invasive species (Lantana, Parthenium, Eichhornia).
• Co-extinctions (plant–pollinator pairs).
• Pollution and climate change.

Q5. Compare in-situ and ex-situ conservation.

• In-situ: in natural habitat; whole ecosystem protected; examples – national parks, sanctuaries, biosphere reserves, sacred groves.
• Ex-situ: outside natural habitat; for highly threatened species; examples – botanical gardens, zoos, seed banks, cryopreservation, tissue culture.
• Both are needed together.
• Mention Vidarbha tiger reserves as local examples.

Exam tip

Use Indian and Maharashtra examples (Tadoba, Melghat, devrai) – they make answers stand out. Learn the zones of a biosphere reserve with a simple circle diagram.

Quick summary

Good seed and healthy planting material are the base of good crops. Seed technology deals with producing, processing, testing, storing and certifying quality seed. A plant nursery raises seedlings and grafts for farms, gardens and forests. This topic covers seed quality, classes of seed, seed testing, dormancy and its breaking, seed storage, and nursery types, structures and propagation methods.

Key points

• Seed – fertilised, ripened ovule with an embryo, food reserve and seed coat. In agriculture, "seed" means any material used for planting (seeds, tubers, cuttings).
• Qualities of good seed: genetic purity, physical purity, high germination percentage, vigour, correct moisture content, freedom from diseases, pests and weed seeds.
• Classes of seed (Indian seed system): Nucleus seed (by the plant breeder) → Breeder seed (golden-yellow tag) → Foundation seed (white tag) → Certified seed (blue tag) → farmers.
• The Seeds Act, 1966 regulates quality of notified seeds in India; seed certification agencies inspect fields and seed lots. (Check current rules – a new Seeds Bill has been under discussion.)
• Seed testing (ISTA rules): sampling; purity test; germination test (between paper, on paper, sand); moisture test; viability test with tetrazolium (TZ) – living tissue turns red; vigour tests.
• Seed dormancy – failure of viable seed to germinate in favourable conditions. Causes: hard seed coat, immature embryo, inhibitors (ABA), need of light or chilling.
• Breaking dormancy: scarification (mechanical scratching or acid treatment), stratification (moist chilling), soaking in water, hormones (gibberellic acid, GA₃), potassium nitrate.
• Seed storage: keep dry and cool; "Harrington's rules" – every 1% fall in seed moisture or 5 °C fall in temperature roughly doubles seed life (within limits). Orthodox seeds tolerate drying; recalcitrant seeds (mango, jackfruit, cocoa) do not.
• Seed processing: drying, cleaning, grading, seed treatment (fungicides, biofertilisers), packing and labelling.
• Nursery – place where plants are raised and cared for until planting. Types: temporary and permanent; by plants – fruit, vegetable, flower, forest and ornamental nurseries.
• Nursery structures and tools: mother plant block, propagation beds, polyhouse/greenhouse, shade net house, mist chamber, polybags, pro-trays, potting mixture (soil + sand + farmyard manure or cocopeat).
• Propagation methods: by seed (sexual) and vegetative – cuttings (rose, hibiscus), layering (air layering/gootee in guava, litchi), grafting (approach, wedge/cleft grafting in mango), budding (T-budding in rose, citrus), and micropropagation (tissue culture).
• Nursery management: seedbed preparation, sowing, watering, shading, hardening, plant protection, record keeping and licensing of commercial nurseries.

Important terms

• Germination percentage – (seeds germinated ÷ seeds tested) × 100.
• Scarification – weakening the seed coat to allow water entry.
• Stratification – keeping seeds moist at low temperature to break dormancy.
• Stock and scion – rooted lower part and upper shoot part joined in grafting.
• Hardening – gradually exposing nursery plants to outside conditions before field planting.

Key facts

• Worked example: 100 seeds tested, 92 germinated → germination percentage = (92 ÷ 100) × 100 = 92%.

5 important questions

Q1. What is the tetrazolium test?

A quick viability test. Seeds are soaked in 2,3,5-triphenyl tetrazolium chloride solution; living tissues reduce it to a red compound (formazan), while dead tissues stay colourless.

Q2. Distinguish between orthodox and recalcitrant seeds.

Orthodox seeds can be dried to low moisture and stored for long at low temperature (wheat, rice). Recalcitrant seeds die if dried and cannot be stored long (mango, jackfruit).

Q3. Describe the classes of seed and seed certification.

Nucleus, breeder, foundation and certified seed; who produces each; tags; field inspection and seed testing standards; Seeds Act 1966.

Q4. Explain seed dormancy and methods to break it.

Types and causes; scarification, stratification, GA₃, KNO₃, light treatment; importance for nursery work.

Q5. Write an account of nursery management and vegetative propagation.

Types of nursery, site and structures, potting mixture; cuttings, layering, grafting, budding with sketches; hardening and plant protection.

Exam tip

Learn the seed class–tag colour table and draw one grafting and one budding diagram – they are frequently asked in skill-based (SEC/VSC) papers too.