Taxonomy : It deals with the study of the methods of identification, nomenclature and classification of the animals.
Adnation : A phenomenon in which organs like leaves, flowers etc. instead of being present at their original place, undergo a shift and are seen away from their original place. Due to this adnation, there is displacement of organs in solanaceae members.
Axile Placentation : Axile placentation is defined as type of placentation where the ovules are arranged on a central axis in the ovary.
Aestivation : It is the arrangement of perianth members in the thalamus of flower in bud condition.
Basal Placentation : A type of placentation where the ovules are attached to the base of the ovary.
Artificial System : This is a system of classification based on artificial and easily comparable characters.
Arnica : A drug obtained from the dried flower heads of Amica montana.
Ascending Imbricate Aestivation : In caesalpiniaceae the flower shows five petals which are overlapped. Ascending imbricate aestivation is the overlapping of petals in ascending order.
Bicarpellatae : A series in the subclass gamopetalae. This series is characterized by the presence of flowers with bicarpellary, syncarpous, superior ovary.
Carolus Linnaeus : A naturalist and physician of Sweden who proposed sexual system of plant classification in his book “Genera Plantarum”. He laid down the foundation of the modern concept of taxonomy, hence regarded as “Father of Taxonomy”.
Coronariae : A series in the class monocotyledons. This series is characterized by the presence of bracteate, pedicellate, complete bisexual, actinomorphic, homochlamydeous, trimerous flowers.
Commissural Stigma : This stigma is found in the members of Brassicaceae.
Bentham and Hooker : George Bentham and Sir J.D. Hooker have been the two great British taxonomists associated with Royal Botanical Gardens at Kew, England. They proposed a comperehensive system of classification of plants in their book “Genera Plantarum” a three volume work in Latin.
Binomial Nomenclature : As the word shows it is the naming of a plant with two words, first word indicates the genus and second word indicates species.
Cruciform Corolla : A type of polypetalous corolla seen in Brassicaceae in which four clawed petals are arranged diagonally in a cross-like manner.
Cypsela : It is a dry indihiscent fruit developed from an inferior, bicarpellary pistil with a single seed and persistent pappus.
Diadelphous Stamens : If the stamens of a flower unite by their filaments forming two bundles, then they are called diadelphous stamens e.g., Tephrosia (9 + 1 stamens).
Descending Imbricate Aestivation : The flower of Fabaceae shows five overlapped free petals where the overlapping proceeds from posterior side to anterior side. This type of aestivation is called descending imbricate aestivation.
Disc Florets : These are small bisexual flowers present in a head inflorescence. They occupy the central position in a head. Disc floret is regular, gamopetalous, epigynous and pentamerous.
Epigynous Flower : Flower in which the ovary is within the receptacle and the other floral parts are attached above it.
Gamopetalae : A subclass of Dicotyledonae. Here the flowers are with united petals and epipetalous stamens.
Head Inflorescence : A characteristic type of inflorescence in Asteraceae. It shows small flowers called florets arranged on a disc like structure. They are protected by involucre of bracts.
Hypogynous Flower : Flower in which the stamens, petals and sepals grow from below the gynoecium on the receptacle.
ICBN : ICBN is a well known “International Code of Botanical Nomenclature”. The principles of plant nomenclature were formulated and published by International Botanical Congress.
Inferae : A series under the subclass gamopetalae. Here the flowers are with bicarpellary, syncarpous, inferior ovary.
Monadelphous Stamens : These are the total stamens of a flower unite by their filaments forming a single bundle, then they are called monadelphous stamens e.g., Crotalaria.
Marginal Placentation : A characteristic type of this placentation is Fabaceae where the ovules are arranged on the margins alternately.
Natural System : A system of classification based on a perfect study of natural relationship of organisms is known as natural system.
Pappus : Modified, reduced, persistent pairy calyx lobes which help in fruit and seed dispersal as parachutes are known as pappus. The family Asteraceae is characterised in having such scaly pappus lobes on its fruit called cypsela.
Phylogenetic System : A system of classification of plants based on their origin and evolutionary relationships is called the phylogenetic system.
Piston Mechanism : The method of pollination seen in papilionaceae (Fabaceae) in which sex organs emerge from keel before pollination by the piston like action of the insect. Hence the name piston mechanism.
Polypetalae : A subclass of Dicotyledons. Flowers of this subclass have free petals.
Perigynous Flower : A flower with cup shaped thalamus having gynoecium arising from the centre with other floral organs from the rim of the cup.
Ray Floret : Ray florets are small unisexual female flowers that occupy peripheral position in a heterogamous head. It consists of gamopetalous zygomorphic corolla where the posterior two petals are reduced and the anterior petals are enlarged.
Replum : A false septum seen in the ovary of Cruciferae by which the unilocular ovary becomes bilocular, bearing the seeds at the time of fruit dehiscence in siliqua or silicula.
Sexual System : This an artificial system of classification purely based on the sex organs of the plants. It is proposed by Linnaeus.
Staminode : A sterile stamen. Staminodes are commonly found in the family Caesalpinaceae.
Swollen Placentation : Swollen placentation is found in the family Solanaceae. Here the ovary consists of an axile placenta which becomes fleshy and bear the ovules.
Taxon : Taxon is the unit in plant classification. The rank of taxon in the classification varies. “Plant kingdom” is the largest taxon and the ‘species’ is the lowest and basic taxon. Genus, family, order, series, class and division are the other taxonomic units.
Tetradynamous : A condition where the flower has sex stamens of which four are longer and two are shorter. The longer stamens are arranged in two pairs. This condition is seen in the flowers of Brassicaceae.
Zygomorphic Flower : A flower which can be cut into two equal halves in one plane i.e., anteroposterior plane is called zygomorphic flower.
Classfication
Classification : Classification is defined as a set of categories to which species are assigned on the basis of their relationship to other species.
Need for Classification
1. Classification helps biologists in the study of plants and animals in an systematic way.
2. It helps us to identify the animals without any confusion.
3. It helps us to acquire knowledge of different kinds of animals, their similarities, differences, inter-relationship and distribution.
4. Classification gives us information regarding phylogeny of life and helps in understanding the evolution of organisms.
5. Thus classification not only gives the systematic position, it also gives us the degree of genetic relationship among the animal groups.
Hierarchy of Classification : The primary categories are kingdom, phylum, class, order, family, genus and species. The intermediate categories are sub-phylum, sub-class, sub-order, sub-family etc. to meet specific needs.
The hierarchy of classification is :
Kingdom
Phylum
Class
Order
Family
Genus
Species.
Species : Species is a group of individuals that resemble closely in their anatomy and interbreed among themselves. They possess the same number of chromosomes. When we write species name, the first letter should be in small letter.
Genus : It occupies the next higher level of classification. Genus (plural—genera) is an assemblage of similar and related species. The first letter of the generic name should be written in capital leter. Both genetic and specific names should be italicised or underlined because these are in Latin.
Family : It is the next taxonomic category which includes one or more related general. They are separated from the related families by some characteristic differences.
Order : It is next higher taxon to family which includes number of related families.
Class : It is the next higher level which includes the organisms of related orders.
Phylum : It is next higher taxon which includes different classes of organisms showing some common features. Phylum is a big group having the animals with same pattern of organization.
Kingdom : It is the highest level in the classification which includes the different phyle.
Classification of Living things
Clide : In clides we consider a common ancestor and all the species descended from this common ancestor.
Cladistics : A school of systematics that determines the degree of relatedness by analyzing primitive and derived characters and constructing cladograms.
Cladogram : In cladistics, a branching diagram that shows the relationship among species in regard to their shared, derived characters.
Common Ancestor : An ancestor held in common by at least two lines of descent.
Convergent Evolution : Convergent evolution deals with similerty in structure in distantly related groups due to adaptation to the environment.
Derived Character : A structural, physiological or behavioural trait that is present in a specific lineage and is not present in the common ancestor for several lineages.
Homology : Similarity in structure due to a common ancestor.
Parallel Evolution : Similarity in structure in related groups that cannot be traced to a common ancestor.
Phylogenetic Tree : A diagram that indicates common ancestors and lines of descent.
Phylogeny : The history of evolution of a group of organisms.
Primitive Character : A structural physiological trait that is present in a common ancestor and all members of a group.
Systematics : The study of the diversity of organisms from the cellular level to the population level.
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