Taxonomical Evidences, Morphological evidences in Taxonomy, 2025-26.pdf

Taxonomical Evidences, Morphological evidences in Taxonomy, 2025-26.pdf

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  P.G. Department ofBotany St. Thomas College, Bhilai BOTANY-PAPER-I : TAXONOMY AND DIVERSITY OF PLANTS Morphological Evidences in Taxonomy AUTHOR - TEJASVAEE KUMAR SHARVA Student of M.Sc 4th Sem., Submitted to and guided by Dr. Suruchi Parkhey, Asst. Professor, P.G. Department of Botany, St. Thomas College, Bhilai, Date of submission 04/October/2024
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  Topic Abridgment 1. Introduction 2.History 3. Types of Morphological Evidences 4. Examples associated with Root 5. Examples associated with Stem 6. Examples associated with Leaf 7. Examples associated with Inflorescence 8. Examples associated with Fruit 9. Significances 10.Conclusions 11.References
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  I. Introduction :- •Morphological Evidences in Taxonomy refers to study of “external appearances” in plants, and establishing relations based on similarities and dissimilarities between them. • Taxonomic evidences are oldest but most trusted tool in plant taxonomy as it is based on directly observable physical evidences. • It is the foundation upon which classical classification systems of plants, like those of Bentham and Hooker system of classifica- tion (1862-1883) was based upon. • While modern system of classification give emphasis on molecular analysis, The mor- phological evidences still serve as simple but effective medium for studying taxonomic re- lations.
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  II. History :- •1.Theophrastus (371 BC to 287 BC) :- Fa- ther of Botany, He was a naturalist, he clas- sified plant on basis of based on their growth habit into herbs, shrubs, and trees. • 2. Carl Linnaeus (1735) :- Published a book named Systema Naturae, It has The Linnae- an artificial system of classification which was based on limited number of observable morphological traits like number of pistils and carpels etc. • 3. Bentham & Hooker’s (1862-1883) :- Published book Genera Plantarum, It was published in three volumes between 1862 and 1883, It consisted of Natural system of classification which was based on observa- ble morphological and some anatomical fea- tures.
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  III. Types ofMorphological Fig 3.1 : Types of Morphological Evidences in Taxonomy
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  IV. Examples associatedwith Root :- The root system provides foundational evidence for high-level classification: • Taproot vs. Fibrous : The presence of a tap- root (developed from the radicle) is a charac- teristic feature of Dicots (e.g., Mangifera indica), whereas a fibrous root system is a hallmark of Monocots (e.g., Oryza sativa). • Modified Roots : Specific modifications de- fine certain groups. For example, Pneumato- phores (respiratory roots) are morphological evidence for halophytes like Rhizophora (Family Rhizophoraceae). • Storage Roots : Fasciculated tuberous roots are a diagnostic feature for genera like Dahl- ia and Asparagus.
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  V. Examples associatedwith Stem :- Stem morphology helps distinguish both habits and specific families: • Growth Habit : The distinction between her- baceous stems (found in almost all Monocots and many Dicot families like Brassicaceae) and woody stems (characteristic of many perennial Dicots and Gymnosperms) is a pri- mary taxonomic filter. • Modified Stems : The presence of a rhizome is a defining morphological character for the family Zingiberaceae (e.g., Ginger, Turmeric). Similarly, phylloclades (flattened, leaf-like photosynthetic stems) are characteristic of xerophytic plants like Opuntia (Family Cac- taceae). • Stem Shape : Square or quadrangular stems are a key diagnostic feature for the family Lamiaceae (e.g., Ocimum sanctum).
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  VI. Examples associatedwith Leaf :- Leaves offer a plethora of diagnostic characters: Venation: Reticulate venation is typical of Di- cots, while parallel venation is the standard for Monocots. • Phyllotaxy : The arrangement of leaves (alternate, opposite, or whorled) is a stable character. For instance, opposite decussate phyllotaxy is a consistent trait in the family Acanthaceae • Leaf Type : Simple vs. compound leaves help identify genera. The palmately com- pound leaf of Bombax ceiba distinguishes it from the pinnately compound leaves found in the family Fabaceae (e.g., Cassia fistula). • Stipules : The presence of an ochreate stip- ule (a tubular sheath) is a unique morpho- logical marker for the family Polygonaceae.
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  VII. Examples associatedwith Inflorescence :- The arrangement of flowers is one of the most powerful tools in plant taxonomy: • Capitulum (Head) : The presence of a capit- ulum inflorescence, where many small flo- rets are crowded on a common receptacle, is the defining morphological evidence for the family Asteraceae (e.g., Sunflower). • Umbel : An umbel inflorescence, where pedi- cels arise from a single point like umbrella ribs, is the signature of the family Apiaceae (e.g., Coriander). • Cyathium : This specialized, cup-like inflo- rescence is a unique identifying feature for the genus Euphorbia. • Spadix : A thick, fleshy spike covered by a large bract (spathe) identifies the family Ara- ceae.
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  VIII. Examples associatedwith Fruits :- Fruit morphology often serves as the final "key" in identification: • Caryopsis : A dry, one-seeded fruit where the seed coat is fused with the pericarp is the standard for the family Poaceae (Grasses/Cereals). • Legume/Pod : A fruit developing from a monocarpellary ovary and dehiscing along two sutures identifies the family Fabaceae. • Siliqua : A long, two-valved fruit character- istic of the family Brassicaceae (e.g., Mus- tard). • Pepo : A fleshy fruit with a hard rind, typical of the family Cucurbitaceae (e.g., Watermel- on, Cucumber).
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  IX. Significances ofstudying morphological evidences :- Morphological evidence is significant for several reasons:  1. Accessibility : It allows for the identifica- tion of plants in the field without the need for expensive laboratory equipment.  2. Stability : Reproductive morphology pro- vides a stable framework for phylogenetic studies and understanding evolutionary re- lationships.  3. Practical Identification : Most "Dichotomous Keys" used by botanists are based almost entirely on morphological characters.  4. Nomenclature : Descriptions required for naming new species (under ICBN/IUCN rules) are primarily based on morphological "Type" specimens.
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  X. Conclusion :- TheMorphological evidences of taxonomy re- main as fundamental and most reliable means for taxonomic studies due to :- • Foundational Framework : Morphology re- mains indispensable for plant identification. • Systematic Organization : Diversity is grounded in measurable features (Roots, Leaves, Fruits). • Validation : Morphological classifications generally align with molecular phylogenetic analyses. • Reliability : Characters like the Legume fruit in Fabaceae or Caryopsis in Poaceae provide stable classification keys.
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  • Bentham, G.& Hooker, J.D. (1862–1883). Genera Plantarum. • Lawrence, G.H.M. (1951). Taxonomy of Vas- cular Plants. Oxford & IBH Publishing. • Singh, G. (2010). Plant Systematics: An Integrated Approach. Science Publishers. • Simpson, M.G. (2019). Plant Systematics. Academic Press Do you have any Questions? References :-