Botany with Rohit Jirobe

  1. Introduction Plant tissues are groups of cells having a common origin and performing specific functions. Broadly, plant tissues are of two types: Meristematic Tissues – actively dividing cells. Permanent Tissues – cells that have lost the power of division and are specialized in function. In addition, plants have Secretory Tissues – responsible for secretion of useful or waste substances. 2. Permanent Tissues Definition : These are tissues formed by the differentiation of meristematic cells. Once formed, they usually lose the ability to divide and perform permanent functions like storage, support, transport, photosynthesis, etc. Types of Permanent Tissues: Simple Permanent Tissues Complex Permanent Tissues Special / Secretory Tissues (discussed separately) 2.1 Simple Permanent Tissues Composed of only one type of cell. Functions: storage, support, photosynthesis, protection. a) Parenchyma Living cells, thin-walled, isodiametr...

1. Sexual Reproduction a. The sexual reproduction involves the union of male and female gametes or two gametangia  b. It has three distinct phases. They are plasmogamy, karyogamy and meiosis. c. The plasmogamy refers to the fusion of two protoplasts that brings two haploid nucle together. d. As a result of plasmogamy a cell containing two haploid nuclei is formed.  e. This cell is known as binucleate cell or dikaryotic cell.  f. The two nuclei residing in that cell are known as a dikaryon.  g. Plasmogamy may be carried out either by gametic union or gametangial contact. h. The next phase is the karyogamy . During karyogamy the two haploid nuclei in a dikaryotic cell fuse together and form diploid nucleus (2N).  I. This nucleus is called a synkaryon . This phase lasts for a short time. It is also known as diplophase. j. Meiosis is the third phase in the sexual reproduction. The diploid nucleus undergoes re-duction division and gives rise to four haploid nucl...

Mode of Reproduction  The production of young ones is called reproduction. There are three modes of reproduction in fungi. They are: 1. Vegetative reproduction 2. Asexual reproduction 3. Sexual reproduction. 1. Vegetative Reproduction In fungi, vegetative reproduction takes place by fragmentation, fission and budding. 1. Fragmentation The plant body of fungi breaks up into many bits called fragments. This process is known as fragmentation. Each fragment grows into a new individual. Fragmentation may occur acci-dentally or spontaneously. 2. Fission The simple splitting of a somatic cell into two daughter cells is known as fission or cell division. Eg. Yeasts. During fission the mother cell elongates. The nucleus of the mother divides into two daughter nuclei. This is followed by the division of the cytoplasm which is known as cytokinesis. A constriction appears in the middle and a cross wall is formed. Two daughter cells are formed. After separation these daughter yeasts are known ...

 1. Asexual Reproduction The reproduction by spores, is called asexual reproduction . The spores are minute cells that serve as reproductive propagules. Spore production is the most common method of reproduction in fungi. There are four types of asexual spores. They are: 1. Conidia 2. Sporangiospores (Endospores) 3. Chlamydospores 4. Arthospores 1. Conidia (singular-Conidium) a. Conidium is a spore formed freely at the tip or side of hypha.  b. Specialized hyphae having such spores are called conidiophores .  c. The tip of conidiophore swells out and produces a spe-cial cell called sterigma (Plural., Sterigmata).  d. The tip of sterigmata cuts off rounded cells called conidia one by one.  e. The conidia germinate and give rise to new mycelia 2. Sporangiospore a. Sp orangiospore or endospore is a spore formed within a sporangium (plural.,sporangia).  b . A sporangium is a sac-like structure within which asexual spores are produced Specialized hyphae havi...