Sexual Reproduction in Flowering Plants The chapter introduces sexual reproduction in flowering plants, focusing on the reproductive units and processes involved.
Structure of Stamen Describes the structure of stamen, including filament and anther. Explains key questions related to attachment points and nature of anther.
Development of Anther Details the development process from archesporial cells to formation of pollen sacs. Discusses important structural features like tetragonal shape, bilobed nature, diethicus characteristic, and tetrasporangiate property.
Anatomy of Anther Wall Explains the anatomy with emphasis on layers such as epidermis, endothelium, middle layers (femoral), tapetum; their functions; role in dehiscence; formation of pollen kit; sporopollenin production for exine formation.
Microsporangium Formation Discusses microspore mother cell differentiation leading to meiosis resulting in four microspores within each microsporangium. Highlights significance regarding male gametophyte development.
Pollen Grain Development Covers polarization process after megaspore selection leading to functional megaspore generation followed by female gametophyte or embryo sac development through free nuclear divisions forming a seven-celled eight-nucleated polygonum type monosporic embryo sac.
Pollination and Inbreeding Devices Genetically, autogamy is self-pollination but ecologically it's cross-pollination. Conditions promoting self-pollination are called inbreeding devices, leading to inbreeding depression. Examples include bisexual flowers, homogamy, klistogamy (closed flower), and bud pollination.
Conditions for Cross-Pollinations Unisexual flowers can show both jitenogamy and cross-pollinations. Heterostyle involves differences in the length of style and stamen; heterospermy supports cross pollinators by not recognizing its own pollen grain; chasmogamous plants support open-flower pollinations.
Examples of Plants with Both Flower Types 'Viola pomelina' & 'Oxalis' have both types of flowers: chasmagamous (open) as well as cleistagamous (closed). Questions may arise about possible outcomes for papaya & date palm due to their dioecious nature or maize being monoecious.
Types of Pollinating Agents 'Biotic agents like insects play a major role in plant pollination.' Wind is also a common abiotic agent while water plays a rare role mainly seen among 30 genera mostly monocots such as vallisneria hydrilla zeus terra etc.
Wind Pollinated Flowers Characteristics include odorless nectar-less colorless light non-sticky pollen grains exposed feathery stigma single ovule per ovary directionless process often seen in cereals belonging to the gramineae family.
Water Pollinated Flowers 'Pollen grains have mucilaginous covering around them so that they don't get damaged by water.' Hydrophily is very rare restricted only to 30 genera especially found amongst monocots like vallisneria hydrilla zeus terra etc.