Sexual Reproduction in Flowering Plants

Vocabulary flashcards covering key terms and definitions related to sexual reproduction in angiosperms, including flower structures, pollination, fertilization, and seed development.

Angiosperms

Flowering plants that exhibit sexual reproduction, developing fruits and seeds as end products.

Inflorescence

The arrangement of flowers on a plant, showing diverse structures adapted for sexual reproduction.

Floral Primordium

The early stage of flower development where hormonal and structural changes initiate differentiation.

Androecium

The whorl of stamens in a flower, representing the male reproductive organ.

Gynoecium

The female reproductive organ of a flower, consisting of pistils.

Stamen

The male reproductive structure in a flower, composed of a filament and anther.

Filament

The long, slender stalk of a stamen that supports the anther.

Anther

The terminal, bilobed structure of a stamen where pollen grains are produced.

Dithecous

Having two theca, referring to the bilobed structure of a typical angiosperm anther.

Microsporangia

Four-sided structures in the anther, located at the corners, where pollen sacs develop.

Pollen Sacs

Developed microsporangia that extend longitudinally through the anther and are packed with pollen grains.

Epidermis

The outermost layer of the microsporangium wall, providing protection.

Endothecium

A wall layer of the microsporangium that aids in dehiscence of the anther.

Tapetum

The innermost wall layer of the microsporangium that nourishes developing pollen grains.

Sporogenous Tissue

A group of compactly arranged homogenous cells in the center of each microsporangium.

Microsporogenesis

The process of formation of microspores from a pollen mother cell through meiosis.

Microspore Tetrads

Clusters of four cells formed after meiotic divisions of sporogenous tissue.

Pollen Grain

Represents the male gametophyte in flowering plants, developing from microspores.

Exine

The hard, outer layer of a pollen grain made of sporopollenin.

Sporopollenin

A highly resistant organic material that makes up the exine of pollen grains.

Germ Pores

Prominent apertures on the pollen grain exine where sporopollenin is absent.

Intine

The inner wall of the pollen grain, composed of cellulose and pectin.

Vegetative Cell

The bigger cell in a pollen grain, containing abundant food reserve and a large, irregularly shaped nucleus.

Generative Cell

The small, spindle-shaped cell in a pollen grain with dense cytoplasm and a nucleus, which divides to form male gametes.

Pistil

The female reproductive part of a flower, consisting of stigma, style, and ovary.

Monocarpellary

Gynoecium consisting of a single pistil.

Multicarpellary

Gynoecium having more than one pistil.

Syncarpous

Pistils fused together in a multicarpellary gynoecium.

Apocarpous

Pistils free in a multicarpellary gynoecium.

Stigma

The landing platform for pollen grains on the pistil.

Style

The elongated, slender part beneath the stigma.

Ovary

The basal, bulged part of the pistil containing the ovarian cavity.

Placenta

Located inside the ovarian cavity, giving rise to megasporangia (ovules).

Megasporangia (Ovules)

Structures arising from the placenta, commonly called ovules.

Funicle

The stalk by which the ovule is attached to the placenta.

Hilum

The junction between the ovule and funicle.

Integuments

Protective envelopes that encircle the nucellus of the ovule.

Micropyle

A small opening at the tip of the ovule, opposite the chalaza.

Chalaza

The basal part of the ovule, opposite the micropylar end.

Nucellus

A mass of cells within the integuments, containing reserve food materials.

Embryo Sac

The female gametophyte located in the nucellus.

Megasporogenesis

The process of formation of megaspores from the megaspore mother cell (MMC).

Megaspore Mother Cell (MMC)

A large cell in the nucellus that undergoes meiotic division to form megaspores.

Monosporic Development

Embryo sac formation from a single megaspore.

Polar Nuclei

Two nuclei situated below the egg apparatus in the large central cell of the embryo sac.

Egg Apparatus

Three cells grouped together at the micropylar end of the embryo sac, consisting of two synergids and one egg cell.

Synergids

Two cells in the egg apparatus with special cellular thickenings called the filiform apparatus.

Filiform Apparatus

Cellular thickenings at the micropylar tip of synergids, guiding pollen tubes into the synergid.

Antipodals

Three cells at the chalazal end of the embryo sac.

Pollination

The transfer of pollen grains from the anther to the stigma of a pistil.

Autogamy

Pollination within the same flower.

Chasmogamous Flowers

Flowers that open and expose the anthers and stigma.

Cleistogamous Flowers

Flowers that do not open at all, ensuring autogamy.

Geitonogamy

Transfer of pollen grains from the anther to the stigma of another flower of the same plant.

Xenogamy

Transfer of pollen grains from the anther to the stigma of a different plant.

Outbreeding Devices

Mechanisms developed by flowering plants to discourage self-pollination and encourage cross-pollination.

Self-incompatibility

A genetic mechanism that prevents self-pollen from fertilizing the ovules.

Monoecious

Having both male and female flowers on the same plant.

Dioecy

Having male and female flowers on different plants.

Pollen-Pistil Interaction

Dynamic process involving pollen recognition followed by promotion or inhibition of the pollen.

Emasculation

Removal of anthers from the flower bud before anther dehiscence.

Bagging

Covering emasculated flowers with a bag to prevent contamination of the stigma with unwanted pollen.

Double Fertilisation

A phenomenon unique to flowering plants, involving syngamy and triple fusion.

Syngamy

Fusion of one male gamete with the egg cell to form the zygote.

Triple Fusion

Fusion of the other male gamete with two polar nuclei to produce a triploid primary endosperm nucleus (PEN).

Primary Endosperm Nucleus (PEN)

The product of triple fusion, which develops into the endosperm.

Endosperm

A tissue filled with reserve food materials used for the nutrition of the developing embryo.

Zygote

The diploid cell formed after syngamy, which develops into the embryo.

Epicotyl

The portion of the embryonal axis above the level of cotyledons.

Plumule

The stem tip or shoot apex of the epicotyl.

Hypocotyl

The cylindrical portion of the embryonal axis below the level of cotyledons.

Radicle

The root tip of the hypocotyl.

Coleorrhiza

An undifferentiated sheath enclosing the radicle and root cap in monocots.

Scutellum

The cotyledon in the grass family, situated towards one side of the embryonal axis.

Coleoptile

A hollow foliar structure enclosing the shoot apex and leaf primordia in monocots.

Non-albuminous Seeds

Seeds with no residual endosperm, as it is completely consumed during embryo development.

Albuminous Seeds

Seeds that retain a part of the endosperm, as it is not completely used up during embryo development.

Perisperm

Residual, persistent nucellus in some seeds.

Parthenocarpic Fruits

Fruits that develop without fertilization.

Apomixis

A form of asexual reproduction that mimics sexual reproduction.

Polyembryony

Occurrence of more than one embryo in a seed.