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How do bryophyte sperm reach the egg?
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bryophyte
Bryophyte moss growing on oak trees.
In bryophytes—which include mosses, liverworts, and hornworts—the transport of sperm to the egg is dependent on the presence of external water, such as rain or heavy dew.123
The process occurs as follows:
- Release: When the plant is wet, the male sex organ, or antheridium, ruptures to release biflagellate sperm into the water.12
- Attraction: Simultaneously, the female sex organ, the archegonium, releases a column of fluid from its neck canal into the surrounding water.1
- Transport: The sperm, which swim in a corkscrew pattern, are chemically attracted to this fluid. They swim toward the site of the highest concentration of the fluid, entering the neck canal of the archegonium to reach the egg located at its base.1
Once the sperm reaches the egg, it burrows into the egg wall, and the nuclei unite to form a zygote, which then develops into the sporophyte generation.13