Lycopodium Life Cycle

Lycopodium or club mosses have two parts to the life cycle, sexual and asexual. Lycopodia are plants that grow in the ground, and sexually reproduce not with pollen and flowers, but with spores. They do, however transport nutrients through xylem and phloem, like other plants, and they send shoots along the ground to seek out and find new areas to live.

Sexual reproduction

In sexual reproduction, rather than reproducing with seeds, the embryo reproduces with a spore. The spore germinates in the soil and the resulting plant, when it reaches maturity, forms a gametophyte, which makes male and female sex cells from male and female sex organs--the female archegonium and the male antheridium. According to the species, the gametophyte may take several weeks to several years to develop.

Anatomy

The lycopodium species require water in order to allow sperm to swim and complete the life cycle. Sperm, formed, by the male part of the plant (antheridium) when they are ready, leave the gametophyte. However, the archegonium, or place where the embryo develops, remains part of the gametophyte.

Development

The fertilized female part of the plant, or archegonium, then forms an embryo or zygote. The zygote forms a sporophyte, which, when mature, releases spores again. Lycopodia take several years to reach sexual maturity, and they produce above ground hanging cones when they are ready to release spores.

Asexual reproduction

Lycopodium branch out and expand through rhizomes, which are actually branches that stretch out and creep along over or under the soil, which seek out new areas of the soil to root and live. Rhizomes form roots, called adventitious roots, which when they send vertical shoots above ground, are the asexually reproducing generations of the lycopodium. New shoots can be formed from rhizomes coming directly out of the sporophyte.

Theories/Speculation

This 'horizontal foraging' of the rhizome although it is effective in the long run by finding new environments for the plant to live in, is costly in terms of energy to the plant, so scientists have shown that the plant makes 'cost-benefit analyses' when deciding whether to grow horizontally, with rhizomes, or vertically, with above ground stems.