Life Cycle of a Moss Plant

The humble moss has a complex reproduction process.

Although many people might not realize and often take it for granted, sexual reproduction comes in a variety of types. Depending upon whether it's an animal or plant, sexual reproduction can include several forms and processes, each reaching the same goal of fertilization and spreading genes. The moss plant features two different types of life cycles, a haploid form and a diploid form, that each allow the plant to propagate into future generations.

Spores

The life cycle of a moss begins with haploid spores that are released from the sporangium---the part of the plant structure that houses spores---of a mature moss plant. Haploid spores are structures---such as the human sperm and egg---that feature only half of their genetic code and have the ability to combine to form a diploid structure. The difference between humans and mosses is that human haploid structures must combine; however, moss haploid structures have the ability to grow on their own.

The individual haploid spores will be either a male or female moss. The spores will undergo mitosis---the process of identical cell division---ultimately developing into a grown male or female gametophyte, or haploid plant, which are each complete with roots, as well as sexual parts.

Sexual Reproducers

The male gametophyte consists of an area known as the antheridia. This area is responsible for producing and holding the sperm of the plant. Ultimately the sperm will be released and will travel to the nearby female moss.

The female gametophyte maintains a sexual reproduction area, known as the archegonia. This region houses the egg, which is a haploid structure that is receptive to the haploid sperm.

Fertilization

One of the key processes in the moss plant life cycle is fertilization. This process involves the sperm leaving the antheridia and traveling to the archegonia, where it enters and fertilizes the egg. The haploid sperm and the haploid egg, now combine to form a diploid zygote. This process is the identical process that humans undergo.

Sporangium

The diploid zygote ultimately grows as an embryo and becomes a young diploid sporophyte. As the sporophyte grows, it begins to stick out of the top of the female gametophyte's structure, featuring a "foot" that leads to a "seta"---which is the portion directly below the top---leading to the "capsule," or "sporangium."

Meiosis and Spore Creation

The sporangium is the key diploid structure of the life cycle. This structure grows and houses mature sporophytes, also known as spores. It creates these spores through the process of meiosis, where genetic exchange of information takes place, ultimately dividing up the genes into many haploid male spores and many other haploid female spores, which are released, beginning the process over again.

References

• The University of Auckland: Mosses: Reproduction
• The University of Cincinnati: Primitive Plants: Mosses, Ferns, and Allies