A fern is a seedless vascular plant which also does not flower. The fronds of ferns pop up in environments all over the world, and all told, thousands of species of plant are classified within the phylum Pteridophyta, which encompasses all of the ferns. In addition to growing wild, the fern is also used as an ornamental plant by humans. Some species of fern provide a source of food, as well.
The fern appears to be one of the earliest vascular plants. Vascular plants have a complex network of veins used to carry water and nutrients throughout the plant as it grows. The evolution of vascular plants such as the fern was an important step in plant history, since it allowed plants to make the jump from algae and small undifferentiated structures to things like flowering plants and trees.
Plants which are recognizable as ferns first appeared millions of years ago. Ferns were especially dominant during the Carboniferous era, most often in the form of giant tree ferns. As the plants died, they mulched and fertilized the soil, making conditions favorable for other plants to grow. These deposits of plants were compressed over millions of years into crude oil, the basis of petroleum products and fuels for modern humans.
Modern ferns range widely in size from very small, delicate specimens to towering tree ferns. They all share the characteristic of branching fronds, rather than traditional leaves. Many ferns have a feathery, lacy appearance which makes them popular as ornamental plants and instantly recognizable for many people. The fern reproduces through spores, which are found on the undersides of the fronds.
As decorative plants, ferns are used in gardens all over the world. Tree ferns are especially popular in the tropics, while more modest species are not uncommon in other places. The fiddleheads of some fern species are edible, leading a small market for these delicately flavored vegetables. A fiddlehead is the tightly furled growth which will eventually uncoil and turn into a frond. When picked before it matures, the fiddlehead is tender and flavorful.
In many forests, ferns are an important part of the ecology. They contribute to the layer of leaf mold and humus on the forest floor which nourishes larger plants and protects the soil. Ferns also provide shelter for wildlife, and serve as a source of food for some animals as well. Humans have used the fern for centuries for things like home insulation and garden mulch, since they exist in such abundance in many parts of the world, especially temperate zones.