annulus: (in ferns) row of specialised cells in a sporangium.

antheridium (pl.antheridia): multicellular structure that produces sperm in bryophytes and ferns.

archegonium (pl.archegonia): multicellular structure that produces eggs in bryophytes, ferns and gymnosperms.

capsule: (in bryophytes) the spore case.

cone: reproductive structure in gymnosperms consisting of tightly packed sporophylls.

diploid: having a chromosome complement consisting of two copies of each chromosome.

egg: the female gamete.

embryo: young animal or young plant sporophyte, while it is still contained within a protective structure, such as a uterus, seed or egg.

endosperm: stored food for the developing plant embryo.

fertilisation: union of gametes.

gamete: mature sexual reproductive cell: the egg or sperm.

gametophyte: (in plants with alternation of generations) the haploid phase which produces the gametes.

generative cell: (1) In many gymnosperms, the cell of the male gametophyte that divides to form the sterile and spermatogenous cells: (2) in angiosperms, the cell of the male gametophyte that divides to form two sperm.

germination: the beginning or resumption of growth by a spore, seed, bud, or other structure.

haploid: having a chromosome complement of just one copy of each chromosome.

integument: in gymnosperms and angiosperms, a layer of tissue around the ovule which becomes the seed coat.

megasporangium (pl. megasporangia): structure that produces the female megaspores.

megaspore: large haploid spore that produces a female gametophyte.

meiosis: division of a diploid nucleus to produce four haploid daughter cells.

micropyle: opening in the integuments of an ovule through which pollen grows to reach the female gametophyte.

microsporangium (pl. microsporangia): structure that produces the male microspore.

microspore: small haploid spore that produces a male gametophyte generative cell.

mitosis: nuclear division in eukaryotes leading to two daughter nuclei with identical chromosome complements.

ovule: organ containing female gametophyte and an egg; mature ovule becomes a seed.

ovuliferous scale: in certain conifers, the appendage or scalelike shoot to which the ovule is attached.

pollen: fertilising element of seed plants, containing the male gametophyte and the gamete, in the stage at which it is shed.

pollen grain: a microspore containing a mature or immature microgametophyte (male gametophyte); pollen grains occur in seed plants.

pollen tube: a tube formed after germination of the pollen grain; carries the male gametes into the ovule.

pollination: in angiosperms, the transfer of pollen from an anther to a stigma. In gymnosperms, the transfer of pollen from a pollen-producing cone directly to an ovule.

prothallus: (in ferns) more or less independent, photosynthetic gametophyte.

protonema: hairlike growth form of an early stage in the development of a moss gametophyte.

rhizoids: hairlike extensions of cells in bryophytes that serve the same function as roots.

seed: fertilised ripened ovule of gymnosperm or angiosperm, consisting of embryo, nutritive tissue and seed coat.

sorus: (pl. sori) group or cluster of sporangia or spores.

sperm: a male reproductive cell.

spermatogenous cell: the cell of the male gametophyte, or pollen grain, of gymnosperms, which divides mitotically to form two sperm.

sporangium (pl. sporangia): specialized structure in which spores are formed.

spore: asexual reproductive cell capable of developing into an adult plant without gametic fusion; haploid spores develop into gametophytes, diploid spores develop into sporophytes.

sporophyte: (in plants with alternation of generations) the diploid phase that produces the spores.

stalk: part of the bryophyte sporophyte.

sterile cell: one of two cells produced by division of the generative cell in developing pollen grains of gymnosperms; it is not a gamete, and eventually degenerates.

zygote: cell formed by the union of two gametes; earliest stage in the diploid generation.