homospory

Homospory is a reproductive strategy in which a plant produces a single type of spore, usually of the same size, known as a homosporous or isosporous condition. The spore germinates to form a single type of gametophyte that typically bears both male and female organs, resulting in a bisexual or hermaphroditic gametophyte.

Homospory occurs in a wide range of land plants, including most bryophytes (liverworts, mosses, hornworts) and the majority of ferns (pteridophytes). Some lycophytes are homosporous as well, such as members of Lycopodiaceae, while others in the group, and several other lineages, have evolved heterospory.

In the life cycle, the sporophyte produces sporangia that release spores into the environment. Each spore germinates into a haploid gametophyte, which typically contains both archegonia (female organs) and antheridia (male organs). Water is usually required for filamentous sperm to swim to the egg and achieve fertilization. The resulting zygote grows into the next sporophyte generation, continuing the cycle.

Evolutionarily, homospory is considered the ancestral condition for many land plants. Heterospory, the production of distinct microspores and megaspores, evolved later in several lineages and is associated with more specialized adaptations of the gametophyte and, in seed plants, with seed formation.