antheridia

Antheridium is the male gametangium, a reproductive organ that produces sperm cells, in certain plants and algae. In non-vascular plants such as mosses, liverworts, and hornworts, and in many ferns, antheridia form on the haploid gametophyte generation and are typically simple, sometimes stalked structures.

Antheridia contain spermatogenous tissue that differentiates into sperm cells, which are usually motile with flagella in bryophytes and ferns. The sperm are released into a thin film of water, and fertilization occurs when they swim to and unite with an archegonium, the female gametangium. The resulting diploid zygote grows into the sporophyte, which is typically dependent on the gametophyte in bryophytes.

Structure and development of antheridia vary among groups. In mosses and liverworts, antheridia are often small, clustered on the gametophyte and sometimes enclosed by a protective jacket. In ferns, they may form on the underside of the gametophyte’s thallus or prothallus and can be stalked or embedded. Some algae also possess analogous male reproductive structures called antheridia, though their organization and dynamics differ from those of land plants.

The term antheridium has historical usage beyond bryophytes and ferns, and it is sometimes applied to male gamete-producing structures in certain algae and fungi. The counterpart to the antheridium is the archegonium, the female gametangium that contains the egg.

In summary, antheridia are the male components of the gametophyte generation in several plant groups, serving to produce and deliver sperm for sexual reproduction in aqueous environments.