Spore

A reproductive or dispersal cell capable of initiating growth without fusion with another cell. In the ordinary land-plant sexual cycle, haploid spores formed by meiosis initiate gametophytes; they are distinct from fusing gametes.

Production of distinct microspores and megaspores that give rise to male and female gametophytes. Retention of developmental stages within spore walls changes protection and provisioning without itself removing the need for water-dependent sperm movement in heterosporous ferns.

A megaspore is the spore type that develops into a female gametophyte in a heterosporous life cycle. It is distinct from an ovum: the megaspore begins a developmental generation, whereas an ovum is a gamete that fuses during fertilization.

The corresponding male-producing spore is a microspore. Following both spore types helps connect heterospory to the strongly reduced gametophytes of seed plants.

The spore type developing into a male gametophyte. Its production is distinct from the later production of sperm.

Production of one principal spore type, as in many ferns. The resulting gametophytes may produce both kinds of gametes, with their actual sexual development depending on the species and conditions.

A resistant wall material in spores and pollen. It helps protect dispersal stages without eliminating the environmental requirements of later development.

Movement of spores away from their source. Resistant walls and elevated release can improve dispersal without guaranteeing germination or successful fertilization in the next generation.