History of Fern Plants

Evolution

• Scientists believe that the ferns and ferns allies descend from now-extinct Rhyniopsida, a group of free-sporing plants that existed about 430 million years ago in the Silurian period. The Rhyniopsida had divided photosynthetic stems that produced sporangia. These primitive vascular plants didn't have leaves or roots. The next group of plants that existed before today's ferns was the Cladoxylales. Even though the group is known as the "pre-ferns," some scientists believe that modern ferns evolved from a different lineage of Rhyniopsida.

Natural History

• Ferns are found in almost all vegetation regions around the world. There are around 11,000 species with the greatest diversity in the tropical and subtropical region from Southern Mexico to Northern America. In warmer climates, many ferns grow as the plants called epiphytes. Epiphytes use other plants and trees for physical support. In temperate climates, the majority of ferns grow as a terrestrial plant in woodlands. Some ferns are aquatic plants that float freely. Regardless of the type of the plant, ferns require rainfall for propagation.

Modern Ferns

• Modern ferns are divided into two evolutionarily distinct groups: the leptosporangiates and the eusporangiates. The first group has the sporangiums that develop from one cell while the sporangiums of the second group develop from several cells. The groups divided about 340 million years ago. While the distinction between the two groups is clear, botanists are uncertain about classification schemes among modern ferns. This is caused by the spread of one specific fern, called polyplodidy, and by the hybridization between some ferns.

Importance to Humans

• Ferns are horticultural plants that grow in gardens or indoors. Ferns and fern allies were the dominant terrestrial plants that contributed to the formation of the fossil fuels, coal, oil and natural gas that we use today as energy sources. Some cultures used fern stems as a food, but some haute cuisine restaurants serve salads with crosiers or fiddle heads of the ostrich fern. There are some ferns used in medicine for ulcer treatments, rheumatism and intestinal infections but there is a little scientific evidence that ferns help in curing.