Plant Reproduction & Seed Development: Key Terms & Structures

sporophyte

The diploid phase of the plant life cycle that produces spores.

gametophyte

The haploid phase of the plant life cycle that produces gametes.

micropyle

A small opening in the ovule of seed plants through which the pollen tube enters.

integument

The outer layer of the ovule that develops into the seed coat.

nucellus

The central tissue of the ovule that contains the megasporocyte.

megasporangium

The structure that produces megaspores in seed plants.

megasporocyte/mother cell

The diploid cell that undergoes meiosis to produce megaspores.

megaspore

The haploid spore that develops into the female gametophyte.

microspore

The haploid spore that develops into the male gametophyte (pollen grain).

polar bodies

Cells produced during oogenesis that do not develop into eggs.

hypocotyl

The part of the seedling that develops into the stem below the cotyledons.

cotyledon

The first leaf or leaves that appear from a germinating seed.

root cap

A protective structure at the tip of a plant root.

radicle

The part of the seed that develops into the root.

endosperm

The tissue that provides nourishment to the developing embryo in seeds.

Coniferophyta

A phylum of gymnosperms that includes conifers, which are cone-bearing plants.

Cycadophyta

A phylum of gymnosperms that includes cycads, which are tropical and subtropical plants.

Ginkgophyta

A phylum of gymnosperms that includes Ginkgo biloba, known for its fan-shaped leaves.

Gnetophyta

A phylum of gymnosperms that includes plants like gnetum, ephedra, and welwitschia.

angiosperm

A group of flowering plants that produce seeds enclosed within a fruit.

fruit

The mature ovary of a flower that contains seeds.

Monocotyledonae

A class of angiosperms characterized by having one cotyledon in the seed.

Eudicotyledonae

A class of angiosperms characterized by having two cotyledons in the seed.

Magnoliophyta

A group of flowering plants also known as angiosperms.

megasporophyll

A leaf-like structure that bears megaspores.

egg cell

The female gamete in plants.

polar nuclei

Two nuclei found in the central cell of the female gametophyte.

synergids

Cells that assist in the fertilization process in plants.

antipodals

Cells located at the opposite end of the egg cell in the female gametophyte.

receptacle

The thickened part of a stem from which the flower organs arise.

epigynous

A flower with the ovary situated below the other floral parts.

hypogynous

A flower with the ovary situated above the other floral parts.

perigynous

A flower with the ovary surrounded by other floral parts at the same level.

calyx

The collective term for the outermost whorl of a flower, consisting of sepals.

corolla

The collective term for the petals of a flower.

androecium

The male reproductive part of a flower, consisting of stamens.

gynoecium

The female reproductive part of a flower, consisting of carpels.

landing pad

A structure that provides a surface for pollinators to land on flowers.

column

A structure formed by the fusion of stamens and styles in some flowers.

pollinia

Masses of pollen grains that are transferred as a unit.

disc flower

A type of flower that has a tubular shape and is often found in clusters.

ray flower

A type of flower that has a flat, petal-like structure extending outward.

inflorescence

A cluster of flowers arranged on a stem.

monoecious

A plant species that has both male and female reproductive structures.

dioecious

A plant species that has distinct male and female individuals.

pollen tube

A tube that forms after pollen germinates and grows toward the ovule.

pericarp

The part of a fruit formed from the ovary wall.

endocarp

The innermost layer of the pericarp that surrounds the seed.

mesocarp

The middle layer of the pericarp.

exocarp

The outer layer of the pericarp.

simple fruit

A fruit that develops from a single ovary.

berry

A type of simple fruit that is fleshy and contains multiple seeds.

drupe

A type of fruit with a hard stone containing the seed.

aggregate

A fruit formed from multiple ovaries of a single flower.

multiple fruit

A fruit formed from the ovaries of multiple flowers.

accessory fruit

A fruit that contains tissues not derived from the ovary.

fleshy

Describing fruits that are soft and juicy.

dry dehiscent

Fruits that split open at maturity to release seeds.

indehiscent

Fruits that do not split open at maturity.

scarification

The process of breaking seed dormancy by damaging the seed coat.

stratification

The process of exposing seeds to cold temperatures to break dormancy.

slash and burn

A method of agriculture that involves cutting and burning plants to create fields.

desertification

The process by which fertile land becomes desert as a result of drought, deforestation, or inappropriate agriculture.

leghemoglobin

A hemoprotein found in the root nodules of legumes that binds oxygen, facilitating nitrogen fixation.

root nodules

Swelling on roots of legumes that contain nitrogen-fixing bacteria.

rhizobium

A genus of bacteria that forms symbiotic relationships with legumes, aiding in nitrogen fixation.

eutrophication

The process by which water bodies become overly enriched with nutrients, leading to excessive growth of algae.

denitrification

The microbial process of reducing nitrates to nitrogen gas, thus removing nitrogen from the soil.

tetraploidy

A condition in which a cell has four sets of chromosomes, often leading to increased size and vigor in plants.

Etiolation

The process by which a plant grows in partial or complete absence of light, resulting in elongated stems and pale leaves.

auxin

A plant hormone that regulates growth, particularly in elongation of cells.

Cytokinin

A class of plant hormones that promote cell division and growth.

Gibberellin

A plant hormone that stimulates stem elongation, seed germination, and flowering.

Abscisic acid (ABA)

A plant hormone that inhibits growth and promotes dormancy, particularly in response to stress.

Ethylene

A gaseous plant hormone that regulates fruit ripening and other growth processes.

IAA (indole-3-acetic acid)

The most common form of auxin, involved in regulating plant growth and development.

apical dominance

The phenomenon where the main central stem of the plant grows more strongly than the side stems.

parthenocarpic fruit

Fruits that develop without fertilization, resulting in seedless varieties.

bolting

The rapid growth of a flowering stalk in certain plants, often triggered by environmental conditions.

dormancy

A period in which a plant's growth and metabolic activity are temporarily stopped.

thigmomorphogenesis

The growth response of plants to mechanical stimulation, such as wind or touch.

photoperiodism

The physiological reaction of organisms to the length of day or night.