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Alternation of Generations
The fluctuation between the diploid (sporophyte) and haploid (gametophyte) life stages that occurs in plants.
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Angiosperm
A vascular flowering plant in which seeds are enclosed inside of protective ovaries.
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Archegonium
The female sex organ of terrestrial plants; where egg cells are produced.
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Bryophyte
A lower terrestrial plant (often a moss or liverwort) that lacks a vascular system and is dependent on environmental moisture for reproductive and nutritive functions.
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Bulb
Roughly spherical underground bud containing additional buds that can develop asexually into new plants. A form of vegetative propagation.
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Cross-pollination
The process, occurring in most angiosperms, by which the male gametes of one plant (carried by pollen grains) fertilize the eggs of another.
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Diploid
Having two sets of chromosomes, one from each parent.
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Double Fertilization
The mechanism of angiosperm fertilization that involves the joining of haploid gametes to create a diploid zygote, and the simultaneous joining of a second sperm cell with a fusion nucleus to create a triploid nucleus (which becomes endosperm).
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Endosperm
A substance, formed from a triploid nucleus in angiosperm reproduction, that nourishes a developing embryo within a seed.
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Fragmentation
A form of vegetative propagation in which a severed plant part develops into a whole new plant.
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Fusion Nucleus
The diploid product formed by the joining of the two polar nuclei in the angiosperm ovule.
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Gamete
A haploid sex cell (either an egg or sperm cell); male and female gametes join during fertilization to create a diploid zygote.
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Gametophyte
A haploid plant or plant structure that produces haploid gametes through mitosis.
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Grafting
An artificial form of vegetative propagation in which parts of two young plants are joined together, first by artificial means and then by tissue regeneration.
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Gymnosperm
A vascular non-flowering plant (commonly known as a conifer) in which seeds are not protected by an ovary.
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Haploid
Having only one set of chromosomes.
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Heterospory
The reproductive phenomenon, characteristic of gymnosperms and angiosperms, whereby spores of two distinct sexes are produced; these spores develop into sex-specific gametophytes.
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Megaspore
Female spore; gives rise to a female gametophyte.
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Meiosis
Cell division that results in cells with half the chromosomes of the parent cell.
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Microspore
Male spore; gives rise to a male gametophyte.
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Ovary
In plants, the protective structure that holds the ovules and surrounds the angiosperm seed; after fertilization, develops into a fruit.
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Ovule
Structure that contains the female gametophyte and gametes; after fertilization, develops into a seed.
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Pistil
The female reproductive organ of the flower, composed of a stigma, style, and ovary; sometimes called the carpel.
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Polar Nuclei
Two nuclei, contained within the same cell, that are created from the mitotic division of the megaspore during angiosperm reproduction; unite in the ovule to form a fusion nucleus, which gives rise to endosperm when fertilized.
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Pollen Grain
The male gametophyte of gymnosperms and angiosperms.
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Pollen Tube
The outgrowth of a pollen grain that creates a path through the female sex organ in order to penetrate to the egg cells.
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Runner
Slender horizontal stem that can give rise, via specialized nodes, to new plants.
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Scale Leaf
Very small structure on the surface of a tuber that contains a bud from which a new plant can arise.
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Scion
Twig or bud that is grafted onto a plant with roots (called the stock) and develops into a new shoot system.
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Self-pollination
The process by which the male gametes of a plant fertilize the eggs of the same plant.
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Sporangium
The part of a plant where spores are produced.
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Spore
Haploid cell from which a gametophyte is produced.
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Sporophyte
A diploid plant or plant structure that produces haploid spores through meiosis.
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Stigma
The top part of the pistil, where pollen grains are received.
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Stock
Plant with a root system onto which a twig or bud from another plant (called a scion) is grafted.
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Tracheophyte
A terrestrial plant with a vascular system.
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Triploid
Having three sets of chromosomes.
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Tuber
Fleshy underground storage structure, composed of an enlarged portion of the stem, that has on its surface buds capable of producing new plants.
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Vascular System
Mechanism of internal water and nutrient transport, characteristic of tracheophytes; made up of the vascular tissues xylem and phloem.
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Vascular Tissue
A conductive component (either xylem or phloem) of the system that transports food and nutrients throughout the plant body.
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Vegetative Propagation
A form of asexual reproduction in which plants produce genetically identical offshoots (clones) of themselves, which then develop into independent plants.
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Zygote
The diploid product of fertilization that develops into an embryo.
