REPRODUCTION IN LOWER AND HIGHER PLANTS

REPRODUCTION IN PLANTS

Reproduction: It is a process by which an organism produces young ones like themselves. It is an essential process for the continuity of generation.

Asexual reproduction: The reproduction which does not involve the fusion of two gametes or sex cells are called asexual reproduction.

Sexual reproduction: The reproduction which involves the fusion of two gametes or sex cells are called sexual reproduction.

Clones: Morphologically and genetically identical individuals are called clones or the organisms produce by asexual reproduction are called clones.

Offspring: organisms produced by means of sexual reproduction is called offspring.

Fragmentation: It is a type of asexual reproduction in which an organism simply breaks in individual pieces at maturity.

Budding:  A form of asexual reproduction in which a new individual develops from some generative anatomical point of the parent organism.

Spore formation: A form of asexual reproduction In which the parent plant produces a large number of spores which individually grow in a plant. these spores are microscopic and round in shape and grow in a suitable condition.

Binary fission: A form of asexual reproduction In which the parent body divides into two equal halves E.g.  Amoeba, Paramoecium.

Conidia  formation: A form of  asexual reproduction in ascomycetes is by the formation of conidia, which are borne on specialized stalks called conidiophores.  E.g. Penicillium.

Gemmules formation: A form of asexual reproduction In which a type of internal bud (gemmule) is formed in sponges to overcome the unfavourable season.

Vegetative reproduction:  A form of asexual reproduction in plants in which new plants grow from some vegetative part (root, stem, leaves) of the plant.

Scion: A living portion of a plant (such as a bud or shoot) joined to a stock in grafting is called the scion.

Stock: A plant in which scion is attached in grafting is called stock.

Tissue culture: It is a growth of tissue or cells in an artificial medium under the control condition is called tissue culture.

Flower: It is a modified shoot meant for the sexual mode of  reproduction is called a flower.

Fertilization: The process of fusion of male and female gametes to form a zygote is called fertilization.

Androecium: Male reproductive unit of the flower is called androecium.

Stamen: The individual member of androecium is called the stamen.

Microsporogenesis: The process of formation of microspore (pollen grain) is called microsporogenesis.

Microspores (pollen grains):  Male gamete produce by the plant is called microspore or pollen grain.

Sporoderm: The wall or the covering of the microspore is called sporoderm.

Exine: The outer tough layer of the sporoderm is called exine.

Sporopollenin: The chemical which forms the exine of a pollen grain is called sporopollenin.

Intine: The inner soft layer of sporoderm is called intine.

Gynoecium: Female reproductive unit of a flower is called androecium.

Carpel: The individual member of gynoecium is called carpel.

Apocarpous:  When all the carpels of fruit, flower or ovary are free from each other then it is called apocarpous.

Syncarpous: When all the carpels of fruit, flower or the ovary are united then it is called syncarpous.

Placenta: The structure by which ovules are attached to the ovary is called the placenta.

Hilum: The scar on a seed which marks the point of attachment to the modified wall of the ovary.

Anatropous: The ovule having bent axis and downwardly directed micropyle is called an anatropous ovule.

Nucellus: The central bulky portion of an ovule which is made up of diploid parenchymatous the tissue is called nucellus.

Integuments: The protective covering of an ovule is called integuments.

Micropyle: The small opening of an ovule through which pollen tube enters into the embryo sac is called a micropyle.

Megasporogenesis: The process of formation of haploid megaspores from diploid megaspore mother cell (MMC) is called megasporogenesis.

Embryo sac: The seven celled and eight nucleated structure of an ovule is called embryo sac.

Monosporic  development: The  method  of development  of the embryo sac  from  a  single  megaspore  is called  monosporic development.

Endosporic development: The method of development of female gametophyte within the megaspore is called  Endosporic development.

Pollination: The transfer of pollen grains from the anther to the stigma of the flower is called pollination.

Self-pollination: A type of pollination which occurs within the same flower or between the two flowers present on the same plant is self-pollination.

Autogamy (self-pollination): A type of pollination in which bisexual flower is pollinated by its own pollen grains is called autogamy.

Chasmogamous: When the flower opens to expose its sex organs, it is called Chasmogamous.

Homogamy: When anther and the stigma of a flower become mature at the same time then it is called homogamy.

Cleistogamy: when flowers are self-pollinated even before the opening of flower then it is called cleistogamy.

Geitonogamy: It is the transfer of pollen grain from an anther to the stigma of a different flower produced on the same plant is called geitonogamy.

Cross-pollination: The transfer of pollen grain from an anther to the stigma of the different flower present on the different plant may or may not belongs to the same species is called cross-pollination.

Xenogamy: It is a type of cross-pollination in which pollen grain of one flower is deposited on the stigma of a flower of a different plant belonging to the same species.

Abiotic agents: The non-living agents performing pollination is called abiotic agents. it includes wind and water.

Anemophily: The pollination that occurs through the air/wind is called anemophily.

Hydrophily: The pollination that occurs through the water is called hydrophily.

Hypohydrophily: A type of hydrophily in which the pollination occurs below the surface of the water is called hypohydrophily.

Epihydrophily: A type of hydrophily in which the pollination occurs on the surface of the water is called epihydrophily.

Biotic Agents: The living agents performing pollination is called biotic agents. it includes insects, birds and bats.

Entomophily: If the pollination is performed by the insect then it is called entomophily.

Ornithophily: If the pollination is performed by the bird then it is called ornithomophily.

Chiropteryphily: If the pollination is performed by the bat then it is called chiropterophily.

Contrivances/outbreeding devices: The adaptations which prevent the self-pollination is called contrivances.

Unisexuality: A type of outbreeding device in which the plant bears either male or female flowers. It is also called as dioecism.

Protandry: A type of outbreeding device in which the androecium matures earlier than the gynoecium is called protandry.

Protogyny: A type of outbreeding device in which the gynoecium matures earlier than the androecium is called protogyny.

Prepotency: Pollen grains of other flowers germinate rapidly over the stigma than the pollen grains from the same flower is called prepotency E.g. Apple.

Heterostyly (heteromorphy): In some plants like Primula (Primrose, there are two or three forms/ types of flowers in which stigmas and anthers are placed at different levels (heterostyly and heteroanthy). This prevents the pollens from reaching the stigma and pollinating it.

Herkogamy: It is a mechanical device to prevent self-pollination in a bisexual flower. In which, a natural physical barrier is present between two sex organs and avoid contact of pollen with the stigma of the same flower.

Self-incompatibility (self sterility): This is a genetic mechanism due to which the germination of pollen on the stigma of the same flower is inhibited.

Pollen - Pistil interaction: All the events that right from the deposition of pollen grains on the stigma to the entry of male gametes into the embryo sac is called pollen-pistil interaction.

Artificial hybridization: The process of crossing two genetically different plants having desirable traits to obtain an offspring having superior traits than parents.

Double Fertilization: the process involving two fertilization in which one of the male gametes fused with the female gamete to form diploid zygote whereas the second male gamete fuses with polar nuclei to form triploid endosperm.

Porogamy: Entry of pollen tube into the embryo sac through the micropyle is called porogamy.

Chalazogamy: Entry of pollen tube into the embryo sac through the chalaza is called chalazogamy.

Mesogamy: Entry of pollen tube into the embryo sac through the integument is called chalazogamy.

Siphonogamy: Transfer of male gamete into the embryo sac through the pollen tube is called Siphonogamy.

Syngamy: The fusion of male and female gamete during fertilization is called syngamy.

Triple fusion: Fusion of haploid male gamete with the diploid secondary nucleus during double fertilization producing primary endosperm nucleus (PEN) is called triple fusion.

Endosperm: The triploid primary endosperm nucleus repeatedly divides, mitotically to form nutritive tissue, called endosperm.

Mosaic Endosperm: Endosperm containing tissue of two different types is called mosaic endosperm. 

Embryogenesis: The process of development of the zygote into an embryo is called embryogenesis.

Haustorium: The first cell of the suspensor towards the micropylar end becomes swollen and function as a haustorium.

Plumule: Part of the embryo which gives rise to the shoot system is called plumule.

Scutellum: The single shield-shaped cotyledon is called as scutellum.

Coleoptile: The protective sheath of plumule is called coleoptile.

Coleorhiza: The protective sheath of the radicle is called coleorhiza.

Testa: The outer tough and resistant seed coat is called tests.

Tegmen: The inner thin and membranous seed coat is called tegmen.

Perisperm: The mass of nutritive material outside the embryo sac is called perisperm.

Pericarp: Pericarp is basically three layers of fruit which may or may not be differentiated into the epicarp (outer layer), mesocarp (middle layer) and endocarp (inner layer).

Dormancy: The temporary suspension of seed germination or the growth of the plant due to unfavourable climatic conditions are called is called dormancy.

Apomixis: It is a phenomenon of formation of the embryo(s) through the asexual mode of reproduction without the formation of gametes and the act of fertilization.

Apogamy: The development of sporophyte from the gametophyte without the fusion of male and female gametes are called apogamy.

Apospory: The development of gametophyte from any cells of sporophyte except spore is called apospory.

Polyembryony: The formation of more than one embryo from a single fertilized ovum or in a single seed is called polyembryony.

Parthenogenesis: The development of an embryo without the fertilization is called is parthenogenesis.

Agamospermy: Here plants produce seeds. But embryo, inside it is produced without meiosis and syngamy.

Parthenocarpy: Formation of fruit without the fertilization is called parthenocarpy. It can be induced artificially by - spraying of gibberellins, delaying pollination, use of foreign pollens, etc.