Sexual Reproduction in Flowering Plants – Key Vocabulary

These vocabulary flashcards cover the essential terms and concepts related to sexual reproduction in flowering plants, as discussed in the lecture notes. Review them to reinforce understanding of structures, processes, and specialised terms from microsporogenesis to seed formation.

Reproduction

Biological process by which organisms give rise to offspring, ensuring survival of the species.

Asexual Reproduction

Type of reproduction involving a single parent and no gamete fusion, producing genetically identical progeny.

Sexual Reproduction

Reproductive process that involves the fusion of male and female gametes, generating genetic variation.

Angiosperm

A flowering plant whose seeds are enclosed within a fruit.

Flower

The reproductive organ of angiosperms, containing structures that produce gametes.

Androecium

Collective term for all stamens (male reproductive organs) in a flower.

Gynoecium

Collective term for all carpels or pistils (female reproductive organs) in a flower.

Stamen

Male reproductive unit consisting of a filament and anther.

Filament

Slender stalk of a stamen that supports the anther.

Anther

Terminal part of a stamen that produces and releases pollen grains.

Microsporangium

Pollen sac inside an anther where microspores develop.

Tapetum

Innermost nutritive layer of anther wall that nourishes developing pollen.

Sporogenous Tissue

Central mass of cells in a microsporangium that gives rise to pollen mother cells.

Microsporogenesis

Meiotic process that converts pollen mother cells into microspore tetrads.

Pollen Grain

Male gametophyte of flowering plants, carrying vegetative and generative cells.

Exine

Hard outer wall of a pollen grain made of sporopollenin.

Sporopollenin

Highly resistant biopolymer forming the exine of pollen grains.

Germ Pore

Thin region in the exine through which the pollen tube emerges.

Intine

Inner wall of a pollen grain composed of cellulose and pectin.

Pistil

Female reproductive organ comprising stigma, style, and ovary.

Stigma

Receptive tip of a pistil where pollen grains land.

Style

Elongated stalk of the pistil connecting stigma to ovary.

Ovary

Basal swollen part of a pistil that contains ovules.

Placenta (botany)

Region inside the ovary to which ovules are attached.

Ovule

Megasporangium that develops into a seed after fertilisation.

Funicle

Stalk that attaches an ovule to the placenta.

Hilum

Junction point where funicle meets the body of the ovule or seed.

Integument

Protective envelope(s) surrounding the nucellus of an ovule.

Micropyle

Small opening in the integuments of an ovule through which pollen tube enters.

Chalaza

Basal region of an ovule opposite the micropyle.

Nucellus

Central tissue of an ovule containing the megaspore mother cell.

Megasporogenesis

Meiosis in the megaspore mother cell producing four megaspores.

Megaspore Mother Cell (MMC)

Diploid cell within nucellus that undergoes meiosis to form megaspores.

Embryo Sac

Female gametophyte of angiosperms, typically 7-celled and 8-nucleate.

Synergid

One of two cells flanking the egg cell that guide the pollen tube.

Filiform Apparatus

Finger-like wall thickenings at the micropylar end of synergids aiding pollen-tube entry.

Antipodal Cells

Three cells located at the chalazal end of the embryo sac.

Polar Nuclei

Two nuclei in the central cell that fuse with a male gamete during triple fusion.

Autogamy

Pollination in which pollen is transferred to the stigma of the same flower.

Geitonogamy

Pollination between different flowers of the same plant.

Xenogamy

Pollination between flowers of different plants; true cross-pollination.

Cleistogamy

Production of closed, self-pollinating flowers ensuring autogamy.

Wind Pollination (Anemophily)

Transfer of pollen via air currents; flowers produce light, non-sticky pollen.

Water Pollination (Hydrophily)

Transfer of pollen through water; rare and seen in some aquatic plants like Vallisneria.

Entomophily

Pollination carried out by insects.

Self-Incompatibility

Genetic mechanism preventing self-fertilisation by inhibiting pollen germination or tube growth.

Pollen–Pistil Interaction

Series of events from pollen landing on stigma to acceptance/rejection and tube growth.

Double Fertilisation

Angiosperm-specific event where one male gamete fuses with egg (syngamy) and the other with polar nuclei (triple fusion).

Syngamy

Fusion of a male gamete with an egg cell forming a diploid zygote.

Triple Fusion

Fusion of a male gamete with two polar nuclei forming the triploid primary endosperm nucleus.

Endosperm

Nutritive triploid tissue formed from the primary endosperm nucleus, supporting embryo development.

Free-Nuclear Endosperm

Type of endosperm where nuclei divide without cell walls before becoming cellular (e.g., coconut water).

Embryo

Young sporophyte developing from the zygote inside a seed.

Scutellum

Single cotyledon of grasses (monocots) functioning in nutrient absorption.

Coleoptile

Protective sheath enclosing the plumule in monocot embryos.

Coleorhiza

Sheath covering the radicle in monocot embryos.

Seed Coat

Hard protective covering of a seed derived from integuments; includes testa and tegmen.

Pericarp

Fruit wall developed from the ovary wall after fertilisation.

False Fruit

Fruit formed from ovary plus other floral parts, e.g., apple (thalamus contributes).

Parthenocarpy

Development of fruit without fertilisation, yielding seedless fruits such as banana.

Apomixis

Asexual formation of seeds without fertilisation, common in some grasses and Citrus.

Polyembryony

Presence of multiple embryos in a single seed.

Emasculation

Removal of anthers from a bisexual flower to prevent self-pollination in hybridisation.

Bagging

Covering of emasculated or unisexual flowers to avoid unwanted pollen contamination.

Panchanan Maheshwari

Renowned Indian botanist who pioneered plant embryology and tissue culture; popularised test-tube fertilisation.