Plants Kingdom | Complete Hinglish NEET Notes | For Free | Class 11 Biology
1. Introduction to Plant Kingdom
Plant kingdom classification ka concept saalon me evolve hua hai jaise-jaise scientific knowledge badhi hai. Pehle ke samay me, organisms jaise fungi aur kuch members Monera aur Protista kingdoms ke Plantae me include kiye jaate the kyunki unke paas cell walls hoti thi. Lekin, aage ki research ne unke cellular structure, reproduction, aur metabolism me bade differences reveal kiye, jiski wajah se unhe plant kingdom se remove kar diya gaya. Ek aisa example hai cyanobacteria, jo pehle blue-green algae kehlaate the. Halanki ye algae jaise dikhte hain, ab ye Monera ke under rakhe gaye hain kyunki ye prokaryotic hain. Isliye, modern plant kingdom ab sirf paanch major groups tak limited hai: algae, bryophytes, pteridophytes, gymnosperms, aur angiosperms.
Early Systems of Classification – The Artificial Approach
Shuru me, plants ko unke visible external features ke basis par classify kiya jaata tha jaise size, shape, color, number of leaves, type of habit (tree, shrub, herb), aur flower parts. Is system ko artificial classification system kaha jaata tha, aur iske sabse notable contributors me se ek tha Carl Linnaeus. In methods me, kabhi-kabhi androecium (male reproductive part of the flower) ka structure hi ek matra criterion hota tha. Lekin, in systems me serious limitations thi. Kyunki ye limited number of traits par focus karte the, bahut saare closely related species alag ho jaate the, aur unrelated species ek saath group ho jaate the. Iske alawa, ye methods vegetative aur reproductive features dono ko equal importance dete the, jo problematic tha kyunki vegetative traits aksar environmental conditions se influence hote hain aur plant ke true evolutionary background ko reflect nahi karte.
Natural Classification – A Better and Balanced Method
Artificial systems ke flaws ko overcome karne ke liye, scientists ne natural classification system develop kiya, jo plants ko broader range of characteristics ke basis par group karne ka aim rakhta tha. Is method me dono, external features aur internal structures, jaise embryology, anatomy, phytochemistry, aur overall morphology, ko consider kiya gaya. Isne plant species ke beech natural relationships ko zyada accurately samajhne me help ki. Flowering plants ke liye sabse accepted natural systems me se ek George Bentham aur Joseph Dalton Hooker ne diya, jinka kaam abhi bhi botanical studies me respect kiya jaata hai. Natural classification ne plants ko genuine similarities ke basis par organize karne me help ki, jis se better taxonomic grouping aur understanding possible hui.
Phylogenetic Classification – Based on Evolution
Aaj ke time me, sabse widely accepted system phylogenetic classification system hai, jo evolutionary relationships ke principle par based hai. Is method ke according, organisms jo same taxonomic group me belong karte hain, unka ek common ancestor hota hai. Ye approach fossil records, molecular biology, aur DNA sequencing se evidence use karta hai taaki different groups of plants ke beech genetic relationships establish ki ja sake. Phylogenetic system plants ke true evolutionary history ko reflect karta hai aur descent aur diversification ke basis par sabse logical grouping offer karta hai. Ye pehle ke methods ke comparison me zyada scientific aur reliable hai.
Numerical Taxonomy – Data-Driven Classification
Modern plant taxonomy ne computer technology me advances se fayda uthaya hai. Ek aisa method hai numerical taxonomy, jahan scientists observable characteristics ke liye numerical values aur codes assign karte hain. Ye data phir computers ke through analyze kiye jaate hain. Is system me har character ko equal importance di jaati hai, aur ye researchers ko ek saath hundreds of features evaluate karne allow karta hai. Numerical taxonomy se zyada objective aur consistent classification achieve karna possible hota hai, khaaskar jab plants overlapping traits dikhate hain.
Cytotaxonomy and Chemotaxonomy – Advanced Scientific Tools
Morphology aur evolution ke alawa, modern taxonomy plants ko zyada accurately classify karne ke liye cellular aur chemical data ka bhi use karti hai.
Cytotaxonomy chromosomes ke number, structure, aur behavior par focus karta hai cell division ke dauran. Ye traits aksar stable hote hain aur species ke beech ke relationships me deep insights provide karte hain.
Chemotaxonomy chemical compounds jaise alkaloids, terpenes, flavonoids, aur plants me paye jaane wale other secondary metabolites ka study involve karta hai. Ye chemicals aksar biochemical markers ke roop me kaam karte hain jo similar-looking plants ko distinguish karne me help karte hain.
Ye advanced methods especially tab helpful hote hain jab fossil records missing ho ya jab external characteristics species ke beech kaafi distinction na provide karte ho. Inka combined use classification ko zyada accurate, scientific, aur evolutionary banata hai.
Conclusion – The Modern Plant Kingdom
Modern understanding of plant kingdom classification old aur new scientific methods ke combination par based hai. Basic visual identification se lekar advanced molecular analysis tak, classification ek complex lekin highly accurate process ban gaya hai. Paanch key groups jo ab officially plant kingdom ka part hain, wo hain algae, bryophytes, pteridophytes, gymnosperms, aur angiosperms. Har group plant evolution ka ek unique level represent karta hai, simple aquatic organisms se lekar highly evolved flowering plants tak jinke paas fruits aur seeds hote hain. Aaj ke classification systems sirf plants ke look par based nahi hain, balki is par bhi ki wo kaise function karte hain, kaise evolve hue, aur unke cells ke andar kya hota hai. Ye comprehensive approach scientists, students, aur researchers ko plant world ki incredible diversity ko logical aur evolutionary tareeke se samajhne me help karta hai.
2. Introduction to Algae – Structure, Types & Reproduction
Algae simple, chlorophyll-containing, autotrophic organisms hain jo mostly aquatic habitats, dono freshwater aur marine, me paye jaate hain. Lekin, ye sirf water bodies tak restricted nahi hain – ye moist surfaces jaise stones, soil, wood par bhi grow karte hain, aur kabhi-kabhi fungi ke sath (jaise lichens me) ya animals ke sath (jaise sloth bear ke body par) bhi rehte hain. Inka body structure, jise thallus bhi kaha jaata hai, usually undifferentiated hota hai aur isme true roots, stems, ya leaves nahi hote.
Algae form aur size me wide range show karte hain. For example, kuch colonial hote hain jaise Volvox, jabki kuch filamentous hote hain jaise Ulothrix aur Spirogyra. Kuch marine algae jaise kelps me body bahut bada aur massive ho jaata hai.
Algae teen tareekon se reproduce karte hain: vegetative, asexual, aur sexual reproduction.
- Vegetative reproduction me algal body fragments me break hota hai, aur har fragment new thallus me grow karta hai.
- Asexual reproduction me spores form hote hain, usually zoospores, jo motile hote hain (flagella ke sath) aur germination ke baad new individuals develop karte hain.
- Sexual reproduction me do gametes fuse karke zygote banate hain. Gametes ho sakte hain:
- Isogamous – gametes size aur shape me similar hote hain. Ye motile (e.g., Ulothrix) ya non-motile (e.g., Spirogyra) ho sakte hain.
- Anisogamous – gametes size me unequal hote hain lekin dono motile hote hain, jaise Eudorina me.
- Oogamous – ek gamete bada aur non-motile (female) hota hai, aur dusra chhota aur motile (male), jaise Volvox aur Fucus me.
Algae ecological aur economic dono hi tarah se bahut important hain. Photosynthesis ke through, algae Earth par nearly 50% total CO₂ fixation perform karte hain, oxygen production me significant contribution dete hain aur aquatic life ko support karte hain. Primary producers ke roop me, ye aquatic food chains ka base hain aur doosre organisms ke liye energy-rich compounds provide karte hain.
Bahut saari algae human food ke liye use hoti hain, especially marine algae jaise Porphyra, Laminaria, aur Sargassum. Total around 70 marine algae species edible hain. Kuch algae jaise brown aur red algae hydrocolloids (water-holding substances) ke sources bhi hain, jaise algin (brown algae se) aur carrageen (red algae se), jo industrial applications me widely use hote hain.
Red algae (Gelidium aur Gracilaria) se ek well-known product agar milta hai, jo labs me microbes grow karne ke medium aur ice-creams aur jellies banane me use hota hai. Ek aur important unicellular alga Chlorella hai, jo proteins me rich hai aur nutritional supplement ke roop me use hota hai, even space travellers ke liye bhi.
Algae broadly teen main groups me classified hain, unke pigments aur other biochemical aur structural characteristics ke basis par:
- Chlorophyceae (Green Algae)
- Phaeophyceae (Brown Algae)
- Rhodophyceae (Red Algae)
Chlorophyceae (Green Algae) – Simplified Notes for NEET | Class 11 Biology
Chlorophyceae, commonly known as green algae, simple aquatic photosynthetic organisms ka ek group hain jo bright green colour ke dikhte hain kyunki inme chlorophyll a aur chlorophyll b present hote hain. Ye pigments randomly scatter nahi hote, balki clearly defined chloroplasts me contained hote hain, jo species ke hisaab se alag shapes ke ho sakte hain — jaise discoid, plate-like, reticulate (net-like), cup-shaped, spiral, ya ribbon-shaped.
Green algae ka structure vary kar sakta hai:
- Kuch unicellular hote hain (single-celled),
- Kuch colonies banate hain (groups of cells living together),
- Aur kuch filaments me exist karte hain (thread-like chains of cells).
Unke chloroplasts me aksar special storage bodies hote hain, jise pyrenoids kaha jaata hai, jo proteins me rich hote hain aur starch store karne me help karte hain. Kuch species me oil droplets bhi reserve food material ke roop me store hote hain.
Unki cell wall kaafi tough aur layered hoti hai — inner layer cellulose se bani hoti hai jo rigidity provide karti hai, jabki outer layer me pectose, ek jelly-like substance, hota hai jo absorption aur protection me help karta hai.
Green algae teen tariko se reproduce karte hain:
- Vegetative reproduction – Ye usually fragmentation ke through hota hai, jahan algal body chhote parts me break ho jaata hai, aur har part new individual me grow karta hai.
- Asexual reproduction – Ye motile spores (zoospores) banane ke through hota hai. Ye flagellated hote hain (movement ke liye tail-like structures) aur zoosporangia (special spore-forming structures) ke andar produce hote hain.
- Sexual reproduction – Green algae me reproduction kaafi diverse hota hai aur ye forms me occur kar sakta hai:
- Isogamous – fusing gametes size aur shape me identical hote hain.
- Anisogamous – gametes size me unequal hote hain lekin dono motile ho sakte hain.
- Oogamous – ek bada, non-motile female gamete fuse karta hai ek chhote, motile male gamete ke saath.
Commonly found examples of green algae:
- Chlamydomonas (unicellular aur motile),
- Volvox (colonial aur motile),
- Ulothrix (filamentous aur non-motile),
- Spirogyra (filamentous with spiral chloroplasts),
- Chara (macroscopic aur highly organized green alga).
Phaeophyceae (Brown Algae) – Simplified Notes for NEET | Class 11 Biology
Phaeophyceae, commonly known as brown algae, mostly marine environments, especially cold coastal waters, me paye jaate hain. Ye algae wide range of forms aur sizes show karte hain. Kuch species simple aur filamentous hote hain jaise Ectocarpus, jabki kuch jaise kelps enormous lengths tak grow karte hain — even 100 meters tak, aur large, branched structures form karte hain.
In algae ka brown colour xanthophyll pigment fucoxanthin ki wajah se hota hai, saath hi chlorophyll a, chlorophyll c, carotenoids, aur other xanthophylls bhi hote hain. Fucoxanthin ki amount ke hisaab se inka colour olive green se dark brown tak vary karta hai.
Food storage ke terms me, brown algae simple sugars store nahi karte. Instead, ye complex carbohydrates jaise laminarin aur mannitol ko reserve food material ke roop me accumulate karte hain. Inke vegetative cells ek cell wall se surrounded hote hain, jo cellulose se bani hoti hai aur externally gelatinous layer of algin se coated hoti hai — ye water hold karta hai aur slimy texture provide karta hai.
Cells ke andar, protoplast me centrally located vacuole, plastids, aur nucleus hota hai. Brown algae ka body structure well organized hota hai — usually ye substratum (surface) se holdfast (root-like) se attached hota hai, uske baad stipe (stalk-like structure) hota hai, aur end me broad, flat, leaf-like frond hota hai jo photosynthesis perform karta hai.
Brown algae teen major ways me reproduce karte hain:
- Vegetative reproduction – fragmentation ke through hota hai, jahan thallus pieces me break hota hai aur har piece new organism develop karta hai.
- Asexual reproduction – mostly biflagellate zoospores ke through hota hai, jo pear-shaped (pyriform) hote hain aur do unequal flagella side me attached hote hain.
- Sexual reproduction – species ke hisaab se isogamy, anisogamy, ya oogamy show karta hai. Oogamous species me gamete fusion ya to water me hoti hai ya oogonium (female reproductive organ) ke andar. Gametes bhi pear-shaped hote hain aur do laterally attached flagella movement ke liye hote hain.
Well-known examples of brown algae:
- Ectocarpus (simple filamentous form)
- Dictyota (branched thallus)
- Laminaria (large kelp-like algae)
- Sargassum (floating seaweed)
- Fucus (flat, leathery thallus)
Rhodophyceae (Red Algae) – Simplified Notes for NEET | Class 11 Biology
Rhodophyceae, commonly known as red algae, easily recognize kiye jaate hain unke distinct reddish colour se, jo pigment r-phycoerythrin ki wajah se hota hai. Ye red pigment dominant hai aur unhe light absorb karne me help karta hai, even deep ocean waters me jahan bahut kam sunlight penetrate karti hai. Halanki kuch species surface ke near payi ja sakti hain, lekin majority red algae marine hote hain aur mostly warm coastal regions me milte hain.
Zyada tar red algae ke multicellular bodies hote hain, aur kuch cases me unka body structure kaafi complex hota hai. Unka thallus (body) soft filaments ya large, leathery sheets ke roop me appear ho sakta hai, species ke hisaab se. Green ya brown algae ke contrast me, red algae me food floridean starch ke form me store hota hai, jo chemically amylopectin aur glycogen jaisa hai – dono complex carbohydrates hain jo energy reserves ke kaam aate hain.
Reproduction ke terms me, red algae ke reproductive cells motile nahi hote:
- Vegetative reproduction fragmentation ke through hoti hai, jahan thallus ka piece break hota hai aur new organism me grow karta hai.
- Asexual reproduction non-motile spores ke through hoti hai, jo water me release hote hain aur new individuals me germinate karte hain.
- Sexual reproduction red algae me hamesha oogamous hoti hai, matlab ek large non-motile female gamete fuse karta hai ek chhote male gamete ke saath, jo bhi non-motile hota hai. Is process ke baad complex post-fertilisation developments hote hain jo next generation form karte hain.
Common aur important examples of red algae:
- Polysiphonia – filamentous red algae with branched structure
- Porphyra – food ke liye use hoti hai (especially sushi sheets)
- Gracilaria – agar ka source, microbial cultures me use hota hai
- Gelidium – commercial agar ka ek aur major source, food aur research industries me use hota hai
3. Bryophytes – Non-Vascular Plants and Their Classification
Bryophytes non-vascular land plants hain jo mosses aur liverworts include karte hain. Ye plants mostly moist, shaded, aur hilly areas me paye jaate hain. Kyunki ye land par grow karte hain lekin sexual reproduction ke liye water chahiye hota hai, inhe “amphibians of the plant kingdom” kaha jaata hai. Inki unique water requirement unhe damp environments se closely tie karti hai, jahan ye primary succession me help karte hain, matlab bare rocks ya soil par ecosystems ka gradual formation.
Plant body of bryophytes algae se zyada advanced hai lekin abhi bhi relatively simple hai. Ye thallus-like hota hai, matlab true root, stem, aur leaf me differentiate nahi hota, aur ye prostrate (lying flat) ya erect ho sakta hai. Ye surface se rhizoids ke through attach hota hai, jo unicellular ya multicellular ho sakte hain. Halanki inke paas true roots, stems, aur leaves nahi hote, lekin kuch bryophytes me leaf-like, root-like, ya stem-like parts ho sakte hain.
Bryophyte ka main plant body haploid hota hai aur gametes produce karta hai, isliye ise gametophyte kaha jaata hai. Bryophytes ke reproductive organs multicellular hote hain. Male reproductive organ ko antheridium kaha jaata hai, jo biflagellate sperm cells produce karta hai, jise antherozoids kehte hain. Female reproductive organ archegonium hota hai, jo flask-shaped hota hai aur ek single egg cell contain karta hai.
Fertilization ke liye water essential hai — antherozoids water ke through swim karte hain aur archegonium tak pahunchte hain. Jab male gamete egg ke saath fuse karta hai, zygote ban jaata hai. Interesting baat ye hai ki zygote immediately meiosis se divide nahi hota. Instead, ye ek multicellular diploid body me grow karta hai jise sporophyte kehte hain. Ye sporophyte gametophyte se attached rehta hai (free-living nahi hai) aur nutrition ke liye gametophyte par depend karta hai kyunki gametophyte photosynthetic hai.
Sporophyte ke andar kuch cells meiosis (reduction division) se haploid spores produce karte hain. Ye spores germinate karte hain aur new gametophyte plants give rise karte hain, thus completing the life cycle.
Halanki bryophytes ka vast economic importance nahi hai, ye ecologically bahut significant hain. Kuch mosses herbivorous mammals, birds, aur doosre animals ke liye food serve karte hain. Ek notable moss Sphagnum hai, jo peat produce karta hai — ye long time se fuel aur live plants aur materials ko transport karne ke liye packing material ke roop me use hota hai kyunki iska excellent water-retention capacity hota hai.
Bryophytes pioneer species bhi hote hain — ye bare rocks ko lichens ke saath colonize karne wale first organisms me se hain. Ye soil formation me vital role play karte hain, rock surfaces ko break down karke area ko higher plants ke growth ke liye suitable banate hain. Dense mats of mosses falling raindrops ki force reduce karte hain aur soil erosion prevent karne me help karte hain.
Structure aur features ke basis par, bryophytes broadly do major groups me classified hain:
- Liverworts
- Mosses
1. Liverworts – Simplified Notes
Liverworts non-vascular plants hain jo generally moist aur shady areas me grow karte hain, jaise streams ke paas, wet soil, marshy places, tree bark, aur dense forests. Inka structure simple aur usually thalloid hota hai, matlab plant body ek flat, green sheet jaisa dikhai deta hai jo jis surface par grow kar raha hai uske close rehta hai. Ek acha example hai Marchantia. Ye thallus dorsiventral hota hai (distinct upper aur lower side) aur tightly ground se attach rehta hai. Kuch liverworts leafy dikhte hain, jahan small leaf-like outgrowths do rows me stem-like structure ke dono sides par arranged hote hain.
Liverworts asexually do main methods se reproduce karte hain:
- Fragmentation – jahan thallus pieces me break hota hai aur har piece new plant me grow karta hai.
- Gemmae formation – Gemmae (singular: gemma) chhote, green, multicellular asexual reproductive bodies hote hain. Ye tiny structures gemma cups me develop hote hain, jo thallus ke surface par present hote hain. Mature hone par, gemmae parent se detach hote hain aur new individual plants me develop karte hain.
Sexual reproduction me, liverworts male aur female sex organs produce karte hain, ya to same thallus par (monoecious) ya alag thalli par (dioecious). Fertilization ke baad, sporophyte develop hota hai, jo structurally teen parts me divided hota hai:
- Foot (sporophyte ko gametophyte se anchor karta hai)
- Seta (stalk)
- Capsule (jahaan spores form hote hain)
Capsule ke andar meiosis hoti hai aur haploid spores bante hain. Ye spores release hote hain aur germinate karke new, independent gametophyte plants banate hain, thus life cycle complete hota hai.
Mosses – NEET Biology Notes (Class 11, Plant Kingdom)
Mosses non-vascular plants hain jo division Bryophyta se belong karte hain aur algae aur vascular plants ke beech life cycle me ek vital link form karte hain. Ye mostly moist, shaded environments me paye jaate hain aur soil formation aur erosion prevention me crucial role play karte hain.
Life Cycle and Dominant Stage
Gametophyte mosses ka dominant, photosynthetic, aur independent stage hai.
Gametophyte ke do distinct stages hote hain:
Protonema Stage:
- Spore se directly develop hota hai.
- Creeping, green, filamentous, aur branched structure hota hai.
- Aksar filamentous green algae jaisa lagta hai.
Leafy Stage:
- Secondary protonema se lateral bud ke roop me arise hota hai.
- Upright, slender axis ke saath spirally arranged leaves hote hain.
- Multicellular, branched rhizoids ke through soil se anchor hota hai.
- Male (antheridia) aur female (archegonia) sex organs bear karta hai.
Reproduction in Mosses
- Vegetative Reproduction:
- Hoti hai through:
- Fragmentation of the leafy gametophyte
- Budding in the secondary protonema
- Sexual Reproduction:
- Sex organs leafy shoots ke apex par borne hote hain:
- Antheridia (male)
- Archegonia (female)
- Fertilization ke liye water chahiye, taki sperm egg tak pahunch sake.
- Zygote develop hota hai sporophyte me.
Sporophyte Structure
- Sporophyte partially gametophyte par dependent hota hai.
- Mosses me ye liverworts ke comparison me zyada developed hota hai.
- Consists of:
- Foot (gametophyte se attach karta hai)
- Seta (stalk)
- Capsule (sporangium, jahaan spores produce hote hain)
- Spores meiosis ke baad capsule ke andar produce hote hain.
- Mosses me elaborate mechanism hota hai spore dispersal ke liye.
Examples of Mosses
- Funaria
- Polytrichum
- Sphagnum
Ecological and Biological Importance
- Soil formation me help karte hain by breaking down rocks.
- Moisture retain karte hain aur soil erosion prevent karte hain.
- Bioindicators of pollution ke roop me use hote hain.
- Sphagnum moss economically important hai (use hota hai as peat).
4. Pteridophytes – First Vascular Plants and Their Adaptations
Pteridophytes ek group hain vascular, seedless plants ka, jo important genera include karte hain jaise horsetails aur ferns. Ye earliest land plants hain jo true vascular tissues—xylem aur phloem—develop karte hain, jo efficient water aur nutrient transport enable karte hain. Ye evolutionary advancement unhe bryophytes se distinguish karta hai. Pteridophytes usually cool, damp, aur shaded environments me thrive karte hain, halanki kuch species sandy soils me bhi adapt kar sakte hain. Ye plants ecological aur economic significance rakhte hain, kyunki ye often medicinal purposes, soil binders, aur ornamental plants ke liye use hote hain.
Bryophytes ke contrast me, jahan gametophyte dominant stage hai, pteridophytes me sporophyte dominant aur independent phase hai. Sporophyte differentiate hota hai into true roots, stems, aur leaves, jisme well-developed vascular tissues hote hain. Leaves ke size aur complexity ke basis par, pteridophytes me microphylls (small leaves, jaise Selaginella) ya macrophylls (large leaves, jaise ferns) ho sakte hain. Leaves sporangia bear karte hain jo sporophylls se associated hote hain—leaf-like appendages jo reproductive organs ko protect karte hain. Kuch plants me, ye sporophylls compact cone-like structures banate hain, jise strobili kehte hain, jaise Selaginella aur Equisetum me.
Sporangia haploid spores produce karte hain meiosis ke through in spore mother cells. Ye spores germinate karke tiny, multicellular, free-living, aur photosynthetic structures banate hain, jise prothalli kehte hain, aur ye gametophyte generation ko represent karte hain. Gametophytes ko survive karne ke liye moist, shaded environment chahiye, kyunki water fertilization ke liye essential hai. Gametophyte male aur female sex organs bear karta hai—antheridia aur archegonia. Male gametes ya antherozoids antheridia se release hote hain aur water me swim karke archegonium tak pahunchte hain, jahan fertilization hoti hai. Resulting zygote develop karta hai new sporophyte me, thus life cycle complete hota hai.
Most pteridophytes homosporous hote hain, matlab ye sirf ek type ka spore produce karte hain jo bisexual gametophytes banata hai. Halanki, kuch genera jaise Selaginella aur Salvinia heterosporous hote hain, producing microspores (male) aur megaspores (female). Ye spores respectively male aur female gametophytes me develop karte hain. Heterosporous pteridophytes ka important evolutionary feature ye hai ki female gametophyte parent sporophyte se attached rehta hai, allowing zygote ko develop karne ke liye embryo female tissue ke andar. Ye adaptation seed habit ki taraf evolutionary step ko mark karta hai, jo later gymnosperms aur angiosperms me appear hota hai.
Pteridophytes broadly four main classes me classified hain morphological aur structural traits ke basis par:
- Psilopsida – e.g., Psilotum
- Lycopsida – e.g., Selaginella, Lycopodium
- Sphenopsida – e.g., Equisetum
- Pteropsida – e.g., Dryopteris, Pteris, Adiantum
5. Gymnosperms – Naked Seed Plants and Reproductive Structures
Gymnosperms ek group hain seed-producing vascular plants ka, jinke seeds naked rehte hain, yani kisi fruit ya ovary wall me enclosed nahi hote. Term ‘Gymnosperm’ Greek se aaya hai, jahan gymnos ka matlab naked aur sperma ka matlab seed hai. In plants me ovules fertilisation se pehle aur baad dono me exposed rehte hain, aur jo seeds later develop hote hain, wo bhi enclosed nahi hote. Gymnosperms mostly medium to tall trees aur shrubs hote hain, jaise giant redwood tree (Sequoia), jo tallest living plant species me count hota hai.
Gymnosperms me tap root system hota hai. Kuch genera jaise Pinus me roots fungi ke saath symbiotic associations banate hain, jise mycorrhiza kehte hain, jo nutrient absorption me help karta hai. Dusre genera jaise Cycas me specialized roots coralloid roots hote hain, jo nitrogen-fixing cyanobacteria ko house karte hain, enabling plant ko poor soils me survive karne me. Stem unbranched ho sakta hai, jaise Cycas, ya branched ho sakta hai, jaise Pinus aur Cedrus. Leaves simple ya compound ho sakte hain. Cycas me pinnate leaves long-lasting hote hain. Conifers me needle-like leaves extreme climates me survive karne ke liye adapted hote hain, jisme thick cuticle, sunken stomata, aur reduced surface area hota hai, jo water loss minimize karta hai dry, cold, ya windy environments me.
Gymnosperms heterosporous hote hain, yani ye do types ke haploid spores produce karte hain—microspores (male) aur megaspores (female). Ye spores sporangia ke andar develop hote hain, jo modified leaves sporophylls par borne hote hain aur cones ya strobili me arranged hote hain.
Male cones, jise microsporangiate strobili kehte hain, microsporangia carry karte hain microsporophylls par, jahan microspores develop hoke pollen grains banate hain. Male gametophyte highly reduced aur non-motile hota hai, aur ye pollen grain ke andar confined hota hai. Ye development microsporangia ke andar hota hai.
Female cones, jise megasporangiate ya macrosporangiate strobili kehte hain, megasporophylls bear karte hain, jo ovules carry karte hain containing megasporangia. Pinus me male aur female cones same plant (monoecious) par hote hain, jabki Cycas me alage plants par hote hain (dioecious). Har ovule me, megaspore mother cell undergo karta hai meiosis aur 4 haploid megaspores bante hain, jisme se sirf ek survive karke female gametophyte me develop karta hai. Ye gametophyte nucellus me embedded rehta hai aur archegonia (female sex organs) bear karta hai.
Bryophytes aur pteridophytes ke contrast me, gymnosperms ke male aur female gametophytes free-living nahi hote. Ye apne respective sporangia ke andar confined rehte hain aur sporophyte se attached hote hain. Fertilization ke time, pollen grains release hote hain microsporangia se aur air currents ke through micropyle (ovule ka opening) tak le jaye jaate hain. Pollen tube pollen grain se grow karke archegonium tak pahunchta hai aur non-motile male gametes deliver karta hai, enabling fertilization of the egg cell. Fertilization ke baad, zygote develop hota hai embryo me, aur ovule mature hoke seed banata hai. Ye seeds naked rehte hain, without kisi protective fruit covering ke.
Quick Recap of Key Features of Gymnosperms:
- Seed-bearing but non-flowering plants.
- Naked seeds (no fruit formation).
- Tap root system with mycorrhiza (Pinus) or coralloid roots (Cycas).
- Heterosporous: Microspores (pollen) and megaspores (ovules).
- Strobili (cones) for reproduction.
- Non-motile sperm delivered via pollen tube.
- No independent gametophyte; gametophytes develop within cones.
- Examples: Pinus, Cycas, Cedrus, Sequoia.
Some More Extra
Gymnosperms mainly belong to the division Pinophyta, with common classes like:
- Cycadopsida (Cycas)
- Ginkgopsida (Ginkgo biloba)
- Coniferopsida (Pinus, Cedrus, Sequoia)
- Gnetopsida (Gnetum, Ephedra)
6. Angiosperms – Flowering Plants with Enclosed Seeds
Angiosperms, also known as flowering plants, represent the most advanced and diverse group in the plant kingdom. Unlike gymnosperms, jahan ovules exposed rehte hain, angiosperms characterized hote hain flowers ke presence se – specialized reproductive structures jahan pollen grains aur ovules develop karte hain.
Ek defining feature ye hai ki angiosperms ke seeds fruit ke andar enclosed hote hain, jo ovary se fertilization ke baad develop hota hai. Ye enclosure developing embryo ko protect karta hai aur seed dispersal me help karta hai through agents like wind, water, aur animals.
Angiosperms bohot diverse hain aur wide variety of habitats me paye jaate hain – from aquatic environments to arid deserts. Ye size me bhi extensively vary karte hain, from microscopic plants like Wolffia (smallest flowering plant) to gigantic trees like Eucalyptus, jo 100 meters se bhi upar grow kar sakte hain.
Inka ecological aur economic importance immense hai; angiosperms humans ko essential resources provide karte hain jaise food grains, vegetables, fruits, fodder, timber, fibers, oils, medicines, spices, aur numerous industrial products.
Seed ke cotyledons ke number ke basis par, angiosperms classified hote hain into two major groups:
- Dicotyledons – two cotyledons.
- Monocotyledons – one cotyledon.
Ye groups sirf seed structure me hi differ nahi karte, balki leaf venation, vascular bundle arrangement, root type, floral parts, aur germination patterns me bhi difference dikhate hain.
Overall, angiosperms dominate karte hain terrestrial vegetation me aur ecological balance maintain karne aur life on Earth support karne me vital role play karte hain.
7. Chapter Summary – Key Concepts and Important Points at a Glance
The plant kingdom broadly classified hai into five major groups: algae, bryophytes, pteridophytes, gymnosperms, aur angiosperms, jahan har ek ek distinct evolutionary level of plant development ko represent karta hai.
Algae simplest hain, predominantly aquatic, autotrophic organisms, jo chlorophyll contain karte hain aur thalloid body structure dikhate hain. Ye Chlorophyceae, Phaeophyceae, aur Rhodophyceae me classified hain, based on pigment composition aur nature of stored food. Algae reproduce karte hain through: vegetative reproduction by fragmentation, asexual reproduction via different types of spores, aur sexual reproduction, jo ho sakta hai isogamy, anisogamy, ya oogamy ke through.
Bryophytes represent karte hain first land plants jo abhi bhi water pe depend karte hain for sexual reproduction. Inka plant body algae se zyada differentiated hai aur root-, stem-, aur leaf-like structures dikhata hai. Ye non-vascular hain aur rhizoids se substrate pe attach hote hain. Bryophytes grouped hain liverworts aur mosses me. Liverworts ka body dorsiventral thalloid hota hai, jabki mosses upright axes aur spirally arranged leaf-like structures dikhate hain. Life cycle me dominant stage hai gametophyte, jo male (antheridia) aur female (archegonia) sex organs bear karta hai. Fertilization se diploid zygote banta hai, jo sporophyte develop karta hai; ye sporophyte gametophyte se attached rehta hai aur haploid spores produce karta hai for reproduction.
Pteridophytes first vascular plants hain, jinme well-developed roots, stems, aur leaves hote hain, saath me xylem aur phloem jaise vascular tissues bhi hote hain. Main plant body hai sporophyte, jo sporangia bear karta hai aur meiosis se haploid spores produce karta hai. Ye spores germinate karte hain into independent, photosynthetic, thalloid gametophytes called prothalli, jo cool, moist environments me survive karte hain. Gametophytes produce karte hain antheridia aur archegonia. Fertilization ke liye water zaruri hai; male gametes swim karte hain archegonia tak to fertilize the egg, jisse zygote banta hai jo new sporophyte me develop hota hai.
Gymnosperms seed-producing plants hain jahan ovules exposed rehte hain before aur after fertilization, isliye inhe naked-seeded plants bhi kaha jata hai. Ye generally medium to tall trees ya shrubs hote hain jaise Pinus, Cycas, aur Sequoia. Ye dominant sporophytic phase dikhate hain with well-developed tap roots, jo mycorrhizal fungi ya nitrogen-fixing cyanobacteria (coralloid roots me) ke sath associate ho sakte hain. Leaves extreme conditions ke liye adapted hote hain, jaise needle-like forms, thick cuticles, aur sunken stomata. Gymnosperms heterosporous hain, producing microspores aur megaspores in male aur female cones (strobili) respectively. Male gametophytes pollen grains ke form me hote hain, jo wind se ovule tak jate hain. Fertilization pollen tube ke through hota hai, aur zygote embryo me develop hota hai, jabki ovule mature hota hai into a naked seed.
Angiosperms, yaani flowering plants, most advanced group hain aur produce karte hain seeds enclosed in fruits. Inke reproductive structures specialized flowers hote hain, jo pollen grains aur ovules bear karte hain. Angiosperms bohot diverse aur widespread hain, from minute Wolffia se leke towering Eucalyptus trees tak. Inka ecological aur economic importance immense hai, providing food, medicine, fuel, timber, aur other resources. Cotyledons ke number ke basis par ye classified hain: dicotyledons (two cotyledons) aur monocotyledons (one cotyledon). Ye group terrestrial flora me dominate karta hai aur life on Earth sustain karne me key role play karta hai.
