1. Core Concepts & Processes
| Keyword | Description |
|---|---|
| Apomixis | A form of asexual reproduction that mimics sexual reproduction; seeds are produced without fertilisation (common in some Asteraceae and grasses). |
| Artificial hybridisation | Plant breeding technique using emasculation and bagging to cross species/genera for desired traits. |
| Autogamy | Self-pollination within the same flower (pollen from anther to stigma of the same flower). |
| Biotic pollination | Pollination by animals (bees, butterflies, flies, beetles, wasps, ants, moths, birds, bats); most common in flowering plants. |
| Chasmogamous flowers | Normal open flowers with exposed anthers and stigma (can undergo cross-pollination). |
| Cleistogamous flowers | Closed flowers that never open; anthers and stigma lie close, ensuring assured autogamy. |
| Double fertilisation | Unique to angiosperms; syngamy (egg + male gamete → zygote) and triple fusion (polar nuclei + male gamete → primary endosperm nucleus) occur simultaneously. |
| Embryogeny | Early stages of embryo development (proembryo → globular → heart-shaped → mature embryo). |
| Free-nuclear endosperm | Initial stage of endosperm development where primary endosperm nucleus undergoes repeated mitotic divisions without cell wall formation (e.g., tender coconut water). |
| Geitonogamy | Transfer of pollen from anther of one flower to stigma of another flower on the same plant (genetically self-pollination). |
| Megasporogenesis | Formation of megaspores from the megaspore mother cell by meiosis inside the ovule. |
| Microsporogenesis | Formation of microspores (pollen grains) from pollen mother cells by meiosis in the microsporangium. |
| Monosporic development | Development of the embryo sac from a single functional megaspore (most common type in angiosperms). |
| Outbreeding devices | Adaptations (dichogamy, herkogamy, self-incompatibility, dioecy) to prevent self-pollination and promote cross-pollination. |
| Parthenocarpy / Parthenocarpic fruits | Development of fruit without fertilisation (seedless fruits); can be induced by growth hormones (e.g., banana). |
| Pollen-pistil interaction | Recognition and acceptance/rejection of pollen by the pistil through chemical dialogue; determines whether pollen tube growth proceeds. |
| Pollination | Transfer of pollen grains from anther to stigma; can be abiotic (wind/water) or biotic (animals). |
| Polyembryony | Occurrence of more than one embryo in a single seed (e.g., orange, mango). |
| Post-fertilisation events | Collective term for endosperm and embryo development, seed and fruit formation after double fertilisation. |
| Pre-fertilisation: Structures and Events | Development of male and female reproductive structures (stamen, pistil, pollen grain, embryo sac) and pollination. |
| Self-incompatibility | Genetic mechanism preventing self-pollen from fertilising ovules by inhibiting pollen germination or tube growth. |
| Syngamy | Fusion of one male gamete with the egg cell to form the diploid zygote. |
| Triple fusion | Fusion of the second male gamete with the two polar nuclei to form the triploid primary endosperm nucleus. |
| Xenogamy | Cross-pollination between flowers of genetically different plants (true cross-pollination). |
2. Male Reproductive Structures & Terms
| Keyword | Description |
|---|---|
| Anther (bilobed, dithecous, tetragonal) | Terminal bilobed part of stamen containing four microsporangia (pollen sacs). |
| Endothecium | One of the four wall layers of microsporangium; helps in dehiscence of anther. |
| Epidermis | Outermost protective layer of microsporangium. |
| Exine | Hard outer layer of pollen grain wall made of sporopollenin (highly resistant). |
| Filament | Slender stalk of stamen that attaches anther to thalamus or petal. |
| Generative cell | Smaller cell in pollen grain that divides to form two male gametes. |
| Germ pores | Apertures in exine where sporopollenin is absent; site of pollen tube emergence. |
| Intine | Inner continuous layer of pollen grain wall made of cellulose and pectin. |
| Male gametophyte | Mature pollen grain (2-celled or 3-celled stage). |
| Microsporangium / Microsporangia | Pollen sacs inside anther where microspores are produced. |
| Microspore mother cell / Pollen mother cell (PMC) | Diploid cells in sporogenous tissue that undergo meiosis to form microspore tetrads. |
| Microspore tetrad | Group of four microspores formed after meiosis. |
| Middle layers | Wall layers of microsporangium that provide protection. |
| Pollen grain (2-celled / 3-celled stage) | Male gametophyte; shed at 2-celled (vegetative + generative) or 3-celled stage. |
| Pollen sacs | Mature microsporangia filled with pollen grains. |
| Pollen tube | Tube that grows from pollen grain through style to deliver male gametes. |
| Sporogenous tissue | Compact mass of cells in centre of microsporangium that gives rise to pollen mother cells. |
| Sporopollenin | Most resistant organic material in exine; protects pollen grains. |
| Stamen | Male reproductive organ of flower consisting of filament and anther. |
| Tapetum | Innermost nutritive wall layer of microsporangium (often binucleate). |
| Vegetative cell | Larger cell in pollen grain with abundant food reserve and irregular nucleus. |
3. Female Reproductive Structures & Terms
| Keyword | Description |
|---|---|
| Antipodals | Three cells at chalazal end of embryo sac. |
| Central cell | Largest cell of embryo sac containing two polar nuclei. |
| Chalaza | Basal part of ovule opposite the micropyle. |
| Egg apparatus | Group of three cells (one egg cell + two synergids) at micropylar end. |
| Egg cell | Female gamete in embryo sac. |
| Embryo sac (7-celled, 8-nucleate) | Mature female gametophyte. |
| Female gametophyte | Embryo sac developed from functional megaspore. |
| Filiform apparatus | Cellular thickenings at micropylar tip of synergids; guides pollen tube. |
| Funicle | Stalk attaching ovule to placenta. |
| Hilum | Junction between ovule and funicle. |
| Integuments | One or two protective envelopes around nucellus of ovule. |
| Locule (ovarian cavity) | Cavity inside ovary containing ovules. |
| Megaspore mother cell (MMC) | Diploid cell in nucellus that undergoes meiosis to form megaspores. |
| Megasporangium (ovule) | Structure inside ovary that contains embryo sac. |
| Micropyle | Small opening in integuments for pollen tube entry. |
| Monocarpellary / Multicarpellary | Gynoecium with one or many carpels (pistils). |
| Nucellus | Central nutritive tissue of ovule containing embryo sac. |
| Ovary | Basal swollen part of pistil containing ovules. |
| Ovule (anatropous) | Megasporangium attached to placenta by funicle. |
| Pistil / Gynoecium | Female reproductive organ consisting of stigma, style and ovary. |
| Placenta / Placentation | Tissue inside ovary to which ovules are attached. |
| Polar nuclei | Two nuclei in central cell that fuse with male gamete during triple fusion. |
| Stigma | Receptive surface of pistil for pollen landing. |
| Style | Elongated part connecting stigma to ovary. |
| Synergids | Two cells of egg apparatus with filiform apparatus. |
4. Post-Fertilisation Structures & Events
| Keyword | Description |
|---|---|
| Albuminous / Non-albuminous (ex-albuminous) seeds | Seeds with/without residual endosperm at maturity. |
| Coleoptile | Hollow foliar structure enclosing shoot apex and leaf primordia in monocot embryo. |
| Coleorrhiza | Sheath enclosing radicle and root cap in monocot embryo. |
| Cotyledons | Seed leaves that store food (two in dicots, one in monocots). |
| Dicotyledonous embryo | Embryo with two cotyledons, embryonal axis, epicotyl and hypocotyl. |
| Dormancy | State of inactivity in mature seeds until favourable conditions for germination. |
| Embryonal axis | Main axis of embryo with plumule and radicle. |
| Endosperm (cellular, free-nuclear) | Nutritive tissue formed after triple fusion; nourishes embryo. |
| Epicotyl | Part of embryonal axis above cotyledons ending in plumule. |
| False fruits | Fruits formed with contribution from thalamus (e.g., apple, strawberry). |
| Fruit (pericarp) | Mature ovary wall after fertilisation. |
| Globular embryo | Early spherical stage of embryo development. |
| Heart-shaped embryo | Intermediate stage in dicot embryo development. |
| Hypocotyl | Part of embryonal axis below cotyledons ending in radicle. |
| Mature embryo | Fully developed embryo ready for germination. |
| Monocot embryo | Embryo with single cotyledon (scutellum), coleoptile and coleorrhiza. |
| Perisperm | Persistent remnant of nucellus in some seeds (e.g., black pepper, beet). |
| Plumule | Embryonic shoot tip. |
| Primary endosperm cell (PEC) | Central cell after triple fusion; develops into endosperm. |
| Primary endosperm nucleus (PEN) | Triploid nucleus formed by triple fusion. |
| Proembryo | Earliest stage of embryo development from zygote. |
| Radicle / Root cap | Embryonic root tip protected by root cap. |
| Scutellum | Single cotyledon in grass family embryo. |
| Seed coat | Hardened integuments protecting the embryo. |
| True fruits | Fruits developing only from ovary. |
| Zygote | Diploid cell formed by syngamy; develops into embryo. |
5. Other Important Terms & Techniques
| Keyword | Description |
|---|---|
| Bagging | Covering emasculated flowers with butter-paper bags to prevent unwanted pollination. |
| Emasculation | Removal of anthers from bisexual flower buds before dehiscence (used in hybridisation). |
| Floriculture | Cultivation of flowers for ornamental, social and cultural purposes. |
| Pollen banks | Storage of pollen grains in liquid nitrogen for crop breeding programmes. |
| Pollen products | Nutrient-rich pollen tablets/syrups used as food supplements. |
| Pollen robbers | Floral visitors that consume pollen/nectar without effecting pollination. |
| Seed banks | Storage of seeds for future use in agriculture/breeding. |
6. Notable People, Plants & Examples
| Keyword | Description |
|---|---|
| Panchanan Maheshwari (1904-1966) | Eminent Indian botanist who popularised embryology, tissue culture and wrote first NCERT biology textbooks. |
| Amorphophallus | Example of plant with tallest flower providing safe egg-laying site for pollinators. |
| Banana | Classic example of parthenocarpic (seedless) fruit. |
| Castor | Example of persistent endosperm in seed. |
| Citrus / Mango | Examples of polyembryony from nucellar cells. |
| Coconut | Example of free-nuclear endosperm (coconut water) and persistent endosperm. |
| Commelina / Oxalis / Viola | Plants producing both chasmogamous and cleistogamous flowers. |
| Date palm (Phoenix dactylifera) | Record of 2000-year-old viable seed. |
| Groundnut / Pea | Examples of non-albuminous seeds. |
| Hibiscus | Common example used for floral structure illustrations. |
| Hydrilla / Vallisneria / Zostera | Examples of hydrophily (water pollination). |
| Lupinus arcticus | Record of 10,000-year-old viable seed. |
| Parthenium (carrot grass) | Causes pollen allergy; invasive weed. |
| Wheat / Rice / Maize | Examples of wind-pollinated plants and cereals with short pollen viability. |
| Yucca | Mutualistic relationship with moth pollinator. |