Plant Systematics, Anatomy and Development/Embryology PDF

PLANT SYSTEMATICS, ANATOMY AND DEVELOPMENT/ EMBRYOLOGY Course code: BOT302 Credit Hours 4(3+1)  Lecture 1: Introduction to plant systematics: aims, objectives and importance What is Plant Systematics? Systematics is the study of phenotypic, genetic and phylogen...

PLANT SYSTEMATICS, ANATOMY AND DEVELOPMENT/ EMBRYOLOGY Course code: BOT302 Credit Hours 4(3+1)  Lecture 1: Introduction to plant systematics: aims, objectives and importance What is Plant Systematics? Systematics is the study of phenotypic, genetic and phylogenetic relationship among taxa Plant systematics is the science of botanical diversity.  From fundamental point of view: study of nature, causes, patterns and trends in variation among taxa From structural point of view: Study of basic taxonomic components and evolution Functional point of view: Study of characters from many fields of evidence for establishing relationship among taxa From developmental point of view: study of variation among taxa for the determination of character correlations and relationship Systematist The systematist is a student, researcher or scholar who studies classifies identifies describe observe or analyze variation within population, species or higher taxa Aims The Primary Aim of Systematics Discover all the branches of the tree of life, document evolutionary changes occurring along those branches, and describe all the species on Earth. Secondary Aims of Systematics To analyze and synthesize information into a classification that reflects evolutionary relationships To organize this information into a useful, retrievable form To gain insight into evolutionary processes that lead to diversity Aims, and objects of natural classification are to name, describe, and arrange plants. This arrangement should show degree of relationship among plants. This degree of relationship is called affinities. Thus, the aim of systematic is to develop affinities among plants. Objectives 1. To prepare a scheme of classification that provide phenetic, natural or phylogenetic relationship among plants 2. To establish a suitable method for identification, nomenclature and description of plants taxa 3. To provide an inventory of plant taxa that suits local or regional needs 4. To create understanding of evolutionary processes 5. To study diversity of organisms and their relationship with other biological branches.  Definitions of Taxonomy: The word finds its roots in the Greek taxis (meaning ‘order’, ‘arrangement’) and nomos (‘law’ or ‘science’). Taxonomy is the science dealing with classification. Taxonomy aims at grouping organisms on the basis of mutual similarities into units called taxa (singular taxon). For example, organisms having the highest similarity are placed in one taxonomic unit, called a species. A group of several species is then assembled into the next higher unit, called a genus (pl. genera). A group of genera is then collected to form the next higher taxon, called a family. Similarly, a group of families form an order, several orders form a class and several classes, a kingdom. Phytography: The branch of botany concerned with the description of plants.  Classification Arrangement of organisms into groups on the basis of similarities The groups are assembled into more inclusive groups until all organisms assembled into single inclusive group In sequence of increasing inclusiveness, the groups are assigned to fixed hierarchy of species, genus, family, order, class and division Process of classification include Assigning appropriate position and rank to new taxon Dividing a taxon into smaller units Uniting two or mora taxa into one Transferring its position from one group to another and altering rank  1. Artificial classification (Theophrastus, Linnaeus) 1. Only a few characters are considered 2. Members of different groups are usually not similar in hereditary pattern 3. Stable classification 4. Provides only limited information 5. Cannot add new work 6. Difficult for identifying a particular species or genera 7. Not related phylogenetically Example: Linnaeus classified plants based on the number, arrangement and fusion of sexual parts, e.g'., in one of his classes he classified plants into Monandria (single stamen), Diandria (two stamens), Triandria (three stamens) and polyandria (more stamens). 2. Natural classification (Example: Bentham and Hooker’s classification) 1. Almost all the characters are considered 2. Members of different groups are mostly similar in hereditary pattern 3. May change with advancement in knowledge 4. Provides plenty of useful information 5. Recent advancement in the field can be added 6. Plant identification easy 7. Closely related to phylogenetically