spore

A small, usually single-celled reproductive body that is highly resistant to desiccation and heat and is capable of growing into a new organism, produced especially by certain bacteria, fungi, algae, and nonflowering plants.

A dormant nonreproductive body formed by certain bacteria in response to adverse environmental conditions.

A usually one-celled reproductive body that can grow into a new organism without uniting with another cell. Spores are haploid (having only a single set of chromosomes). Fungi, algae, seedless plants, and certain protozoans reproduce asexually by spores. Plant spores that are dispersed by the wind have walls containing sporopollenin.

See more at alternation of generations.

A similar one-celled body in seed-bearing plants; the macrospore or microspore. The macrospore of seed-bearing plants develops into a female gametophyte or megagametophyte, which is contained within the ovule and eventually produces the egg cells. (The megagametophyte is also called the embryo sac in angiosperms.) The microspore of seed-bearing plants develops into the male microgametophyte or pollen grain. See endospore.