Archegonium

An archegonium is a multicellular female reproductive organ in bryophytes, ferns, and many other plants. It houses an egg and is the site of fertilization.

Alternation of generations: A life cycle that alternates between multicellular haploid and diploid phases. The archegonium belongs to the haploid gametophyte phase.
Archegonium neck: The narrow, multicellular upper part of an archegonium that leads toward the egg. Its canal provides the passage sperm must traverse to reach the egg.
Moss: A small, nonvascular land plant whose life cycle is dominated by the gametophyte. Mosses bear archegonia on leafy gametophytes, often in clusters.
Land plant: A member of the plant lineage adapted to life on land, including bryophytes and vascular plants. Archegonia are a reproductive feature shared by several major land-plant groups.
Gametophyte: The haploid, multicellular plant generation that produces gametes. Archegonia develop on the gametophyte and produce its female gamete.
Chemotaxis: Directed cell movement in response to a chemical concentration gradient. Chemical cues from the archegonium help guide sperm toward its opening.
Liverwort: A nonvascular land plant in the division Marchantiophyta. Liverwort archegonia may be elevated on distinctive reproductive structures.
Embryophyte: A land plant whose embryo develops while attached to and nourished by the parent gametophyte or sporophyte. The archegonium helps protect the developing zygote in many embryophytes.
Oogamy: A reproductive pattern in which a large, immobile egg is fertilized by a smaller, motile sperm. The archegonium protects the large egg characteristic of oogamy.
Sperm cell: A male reproductive cell that can fuse with an egg cell. Motile sperm enter the archegonium and travel down its neck.

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