Pollen Vs. Spore

Moss

Pollen and spores are two major means by which vascular plants reproduce. These two methods of reproduction occur in just about just all life forms that exist in the plant kingdom. Only within the one-celled organisms of the plant world is there a form of reproduction that does not involve spores or pollen.

Evolutionary History

Spore reproduction that is found in the mosses, ferns and horsetails has existed on the planet longer than the more recently evolved pollen-induced fertilization that occurs in conifers and flowering plants. A quick look at the fossil record of plants will confirm this.

Time Frame

Fertilization in seed plants occurs on and within the plant only after the pollen has been released and is able to find its way to the female part of the flower. On the other hand spore fertilization cannot occur until after the spores are released from the plant and they find a favorable environment to grow and then reproduce.

Self Pollination

Spore producing plants have a much higher rate of self-fertilization than do the large group of plants that produces pollen. Self-fertilization limits genetic diversity because the genetic code contained in the male and female parts of the same plant will be very similar.

The Durable Seed

Seeds are produced within the pollinated plant and then released to the environment, where in many cases they are capable of remaining dormant for a long time until proper growing conditions occur. However in spore plants, growth of the new plant takes place immediately after the union of the male and female cells.

Distances

Since pollination is often aided by the presence of insects and even a few birds (usually a hummingbird), the act of fertilization can occur over greater distances and require less quantities of the genetic material to be successful.

Reproductive Challenges

Pollen is produced by the male part of the flower, while spores have yet to differentiate into the male and female parts of the plant. This development occurs only after the spore has been released from the plant and then found a favorable micro-environment for growth.

References

• Georgia SW State U: Spore Bearing Plants
• San Francisco State U.: Comparison of Seeds and Spores
• University College London: Spores and Pollen