Ch 5Taxonomy and Systematic Botany — Class 11 Botany, concept-first.

Plants have been the constant companions of human life, supplying food, energy, shelter, clothing, drugs, beverages, oxygen, and enriching our aesthetic surroundings.

Every human being classifies things - food, clothes, books - from the cradle to the grave, but as formal disciplines Taxonomy and Systematics are distinct even though people often use the two words as…

Carolus Linnaeus introduced the taxonomic hierarchy - the arrangement of taxonomic ranks in descending order, from the broadest (Kingdom) down to the narrowest (Species).

Species is the fundamental unit of taxonomic classification - a concept going back to Plato's Greek notion of 'eidos', and defined by Stebbins (1977) as the basic unit of the evolutionary process.

Nomenclature is the act of assigning a name to a plant, governed by the International Code of Nomenclature (ICN - renamed from the International Code of Botanical Nomenclature, ICBN, at the 18th Inter…

The ICN's second principle requires every scientific name to be tied to a physical specimen or illustration called the nomenclatural type (e.g.

Taxonomic aids are the tools, techniques and stored information that help identify and classify organisms, needed across almost every branch of biology.

A botanical garden is specifically a centre for collecting and maintaining plants through their various stages of living - not every attractive garden qualifies.

A herbarium is a store-house of preserved plant collections - a Herbarium Specimen is a pressed and dried plant sample permanently glued/strapped to a sheet of paper, together with a documentation lab…

Just as an unsorted library makes finding one book take hours, while books shelved by genre make it a ten-minute job, the vast assemblage of plants in the world is unstudiable unless it is organised.

Classification is not simply administrative filing - it exists because of three real needs. First, understanding how organisms are classified gives insight into other biological fields and has genuine…

Taxonomic entities have historically been classified in three fundamentally different ways. Artificial classification groups organisms using just one or two easily-observed, convenient characters (e.g…

Carolus Linnaeus (1707-1778), the Swedish botanist known as the 'Father of Taxonomy', outlined an artificial classification - his 'sexual system' - in Species Plantarum (1753), where he listed and des…

Botanists who came after Linnaeus realised that no single character (like stamen count) deserves more weight than any other - this insight sparked the approach to a NATURAL system of classification in…

Charles Darwin's Origin of Species (1859) gave the direct stimulus for phylogenetic classification - arranging taxa specifically to reflect their evolutionary descent, rather than convenience (artific…

APG (Angiosperm Phylogeny Group) classification is the most recent system for flowering plants, based on phylogenetic DATA rather than morphology alone, published across four successive versions - APG…

Taxonomists now agree that morphological characters alone are not sufficient for systematic classification of plants - a complete taxonomy draws on the principles of many disciplines: Cytology, Geneti…

Chemotaxonomy is the scientific approach to classifying plants on the basis of their biochemical constituents - the medicines, spices and preservatives obtained from plants first drew taxonomists' att…

Biosystematics is defined as 'Experimental, ecological and cytotaxonomy' - the study of life forms and the definition of their relationships.

Chromosomes are the carriers of genetic information, and growing knowledge about them has been used for extensive biosystematic studies and for resolving many taxonomic problems.

Systematic serology, or serotaxonomy (also called immunotaxonomy), originated towards the end of the 20th century alongside the discovery of serological reactions and the growth of immunology as a dis…

Molecular taxonomy (molecular systematics / molecular phylogenetics) is the branch of phylogeny that analyses hereditary molecular differences - mainly in DNA sequences - to gain information and estab…

DNA barcoding works much like a supermarket scanner reading a Universal Product Code (UPC) - it uses a very short, standard genetic sequence (a 'DNA tag' or 'DNA barcode') from a fixed part of the gen…

Classical (Alpha/old-systematics) taxonomy is pre-Darwinian: it treats species as a static basic unit and classifies mainly using morphological characters, drawing conclusions from the observation of…

Cladistics (from the Greek klados, 'branch') is the method of classifying organisms into MONOPHYLETIC groups of a common ancestor, based on shared, derived (apomorphic) characters.

The plant kingdom is vast and endlessly varied, and has been organised over time into Artificial, Natural, Phylogenetic and APG systems - the Bentham and Hooker natural system was followed in India un…

Fabaceae (Pea family) includes about 741 genera and more than 20,200 species, cosmopolitan but most abundant in tropical/subtropical regions.

Apocynaceae (milk weed family, including Asclepiadaceae under APG) has about 345 genera and 4,675 species, mostly tropical/subtropical.

Solanaceae (Potato/Nightshade family) has about 88 genera and 2,650 species (Solanum alone contributes ~1,500 species), worldwide but most abundant in South America.

Euphorbiaceae (Castor/Spurge family; APG excludes Peraceae, Phyllanthaceae and Picrodendraceae from it) has 214 genera and about 5,600 species, well represented in Africa and South America.

Musaceae (Banana family) is a small family - only 2 genera, Musa and Ensete, and 81 species - found mainly in wet tropical lowlands from West Africa to the Pacific; APG has separated the four genera R…

Liliaceae (Lily family), in the old wide sense used by Bentham and Hooker, comprises about 15 genera and 550 species distributed worldwide - but APG narrows the family down to just Lilium and Tulipa,…

This chapter-end Evaluation set covers ten questions spanning the whole chapter: nomenclatural types (Neotype), why phylogenetic classification is favoured, serotaxonomy's basis in immune-system compa…

Sample papers and previous-year board questions for this subject.