Around the world, between 10,000 to 12,000 fern species grow. Found on every continent except Antarctica, the fern is an ancient plant that has existed for almost 350 million years, according to the Tropical Fern and Exotic Plant Society. All fern species are considered "vascular plants" because of their highly developed internal structure. The fern's highly evolved internal system allows the plant to utilize water and nutrients with exceptional flow ability.
Ferns require adequate moisture to successfully reproduce genetically diverse offspring. They do not produce flowers nor do they produce seeds for reproduction. Ferns reproduce using capsules known as gametophytes on the underside of their fronds that produce spores. Within the gametophytes exist antheridium which house the sperm and archegonium which contain the egg. Droplets of moisture allow the sperm to exit the antheridium and swim to the egg in the archegonium.
Fertilization occurs much like mammal fertilization. The sperm enters the egg cell. The fusion of genetic material from the sperm and the egg creates a tiny fern within the spore. Upon fertilization the gametophyte is transformed into a sporophyte.
Other Reproduction Means
Ferns located in drier climates can reproduce without typical fertilization. The gametophyte turns into a sporophyte without fertilization from the sperm. This process is rare and called "apogamy" when it occurs. A few fern species also reproduce by spreading rhizomes which create baby plants. Other species can have the very tip of their frond touch the soil, take root and create a smaller plant. Ferns that reproduce using these means produce young offspring that is genetically the same as the parent plant.
The fronds and rhizomes of most species of ferns are coated in tiny hairs. These hairlike structures act as a defense against insects, mammals or reptiles who might harm the plant. On certain varieties of ferns the small hairs contain a toxic substance, emit a foul unpleasant odor or produce a waxy substance.
Fern species play a valuable part in the environment. Many help prevent soil erosion with their strong rhizomes and roots. The root system of the plant also adds valuable moisture to the soil.