Sexual Reproduction in Flowering Plants - Key Vocabulary

Vocabulary flashcards covering anatomy, processes, and key concepts in flowering plant reproduction from flower structure to seed and fruit development.

Angiosperm

A flowering plant whose ovules develop inside an ovary and are enclosed by a carpel, forming seeds inside a fruit.

Stamen

Male reproductive organ of a flower consisting of a filament and an anther that contains pollen-producing structures.

Anther

The bilobed part of the stamen that houses pollen sacs (the theca) where pollen grains develop.

Filament

The stalk that supports the anther in the stamen.

Theca

Pollen sacs within each lobe of a bilobed anther.

Microsporangium

Pollen sac where microsporogenesis occurs to produce microspores.

Tapetum

Innermost wall layer of the microsporangium that nourishes developing pollen grains.

Sporogenous tissue

Central group of cells in the microsporangium that give rise to microsporocytes.

Microsporogenesis

Meiotic formation of microspores from microsporocytes (microspore mother cells).

Microspore tetrad

A cluster of four microspores produced after meiosis.

Pollen grain

Male gametophyte produced from a microspore; typically 2- or 3-celled at shedding, with vegetative and generative cells in many species.

Exine

Hard outer wall of a pollen grain made of sporopollenin, often with germ pores.

Sporopollenin

Extremely resistant biopolymer forming the pollen grain’s outer wall (exine).

Germ pore

Opening(s) in the pollen exine through which the pollen tube emerges.

Intine

Inner wall layer of the pollen grain, composed mainly of cellulose and pectin.

Vegetative cell

Larger pollen cell that governs pollen tube growth and carries food reserves.

Generative cell

Smaller pollen cell that divides to form sperm cells in many species.

Pollen tube

Tube that grows from a germinated pollen grain through the style to deliver sperm cells to the ovule.

Megasporangium (Ovule)

Structure in the ovary that contains nucellus and gives rise to megaspores (female side).

Megasporogenesis

Meiotic formation of megaspores from the megaspore mother cell; usually one functional megaspore forms the embryo sac.

Megaspore

Haploid cell produced by megasporogenesis; typically one becomes the embryo sac.

Embryo sac

The female gametophyte inside the ovule; usually 8-nucleate and 7-celled in many angiosperms.

Monosporic development

Development of the embryo sac from a single functional megaspore.

8-nucleate embryo sac

Embryo sac with eight nuclei organized into three antipodals, two synergids, one egg cell, and two polar nuclei.

Egg apparatus

Structure at the microphylar end of the embryo sac composed of two synergids and one egg cell.

Synergids

Two cells adjacent to the egg cell in the embryo sac that help guide the pollen tube via filiform apparatus.

Antipodals

Three cells at the chalazal end of the embryo sac that support the embryo sac; often degenerate.

Polar nuclei

Two nuclei in the central cell of the embryo sac that fuse with a sperm to form the primary endosperm nucleus.

Central cell

The large central cell in the embryo sac containing the two polar nuclei; becomes endosperm after fertilization.

Pollination

Transfer of pollen grains from the anther to the stigma of a flower, enabling fertilisation.

Autogamy

Self-pollination within the same flower; often requires synchrony of pollen release and stigma receptivity.

Chasmogamous

Open flowers with exposed stamens and stigmas, typically enabling cross-pollination.

Cleistogamous

Closed flowers that never open; undergo self-pollination with assured seed set.

Geitonogamy

Pollen transfer from one flower to another flower of the same plant.

Xenogamy

Pollen transfer between flowers of different plants; fertilisation by genetically distinct pollen.

Pollination agents

Biotic (animals) and abiotic (wind, water) factors that facilitate pollination.

Wind pollination

Pollination by wind; flowers are often non-colored with exposed stamens and large stigmas.

Water pollination

Pollination by water; pollen transported in water, common in a few aquatic taxa.

Animal pollination

Pollination mediated by animals (bees, butterflies, birds, etc.) with rewards like nectar.

Endosperm

Triploid nourishing tissue formed after triple fusion that nourishes the developing embryo.

Double fertilisation

Two fertilisation events in angiosperms: syngamy (egg + sperm) and triple fusion (central cell + sperm).

Syngamy

Fusion of a sperm with an egg cell to form a zygote.

Triple fusion

Fusion of a second sperm with the two polar nuclei to form the primary endosperm nucleus (PEN).

Zygote

Diploid cell formed by syngamy; develops into the embryo.

Seed

Mature ovule containing the embryo and usually endosperm, with a protective seed coat and reduced water content.

Pericarp

The wall of the ovary that becomes the fruit wall.

False fruit

Fruit developing partly from non-ovarian tissue (e.g., thalamus) rather than solely from the ovary.

Parthenocarpy

Fruit development without fertilisation, often yielding seedless fruits.

Apomixis

Asexual seed formation without fertilisation; seeds are genetic clones of the parent.

Polyembryony

More than one embryo develops within a single seed.

Integuments

Outer protective layers surrounding the nucellus that become the seed coat.

Nucellus

Nutrient tissue inside the ovule surrounding the megasporocyte.

Micropyle

Small opening at the apex of the seed coat enabling entry of water and pollen tube access.

Funicle

Stalk attaching the ovule to the placenta inside the ovary.

Hilum

Junction between the ovule and the funicle; marks attachment point.

Ovary

The pistil’s basal portion containing ovules; develops into a fruit after fertilisation.

Placentation

Arrangement of ovules on the placenta inside the ovary (e.g., axile, parietal, free-central).