Where ferns grow

Ferns grow mostly in the tropics. The greatest variety of these plants are found in tropical rain forests and thick forests made up of tall broad-leafed trees. The Arctic and Antarctic regions of the Earth have only a small number of ferns. Many fern species grow on trunks and branches of trees. Others grow on bogs and marshes. The most famous fern is bracken, which grows in abandoned fields and pastures in both temperate and tropical regions.

Some fern species have been introduced into the subtropical areas of the United States, such as southern Florida and Hawaii. They include the giant polypody, climbing ferns, green cliff brake, silver fern, and Japanese holly fern.

Physical features

Ferns occur in many different sizes. Some range from tiny plants measuring ⁸/₁₀₀ to ¹²/₁₀₀ inch (2 to 3 millimeters) in height to tall tree ferns that measure 30 to 80 feet (10 to 25 meters) in height. Some of them wind themselves around trees while others float on the surface of ponds.

Ferns are identified by the featherlike shape of their leaves, called fronds. These leaves have a single midrib with small leaflets branching off from both sides. The leaflets have either toothed or rounded edges. Young fronds are tightly curled. When they grow and begin to unfurl, they resemble the neck of a violin. Therefore, fronds are also known by the popular name fiddlehead.

Life cycle

Ferns existed on Earth before flowering plants. They date back to prehistoric times, some 200 million years ago, when vast forests of giant tree ferns grew in hot and swampy regions. A typical fern consists of three parts: the stem, the leaf, and the root. It produces spores, or reproductive cells, from which a new plant is born. These are located underneath the leaves of the plant as a cluster of spores. When the spores turn ripe, millions of them are released and scatter into the air in the form of fine dust. When carried by wind currents, a small number of them fall on damp surfaces and soils. Here they form into a small, flat, kidney-shaped body. This body gets its food by pushing roots into the soil.

Eventually, this plant body grows male and female organs. Sperm from the male organ fertilizes an egg from the female organ, and this produces a new plant. The new plant produces spores, and the process begins again. This is called alternation of generations since one generation is produced by spores and the next by a fertilized egg. The cycle of development continues with the species fertilizing itself indefinitely. It is for this reason that ferns are spread over larger distances than seed plants.

Uses and harmful effects

Ferns are mainly used as ornamental plants to decorate homes and gardens. They are frequently displayed as potted houseplants and their leaves are used to make bouquets and wreaths. Ferns have limited uses as food. Only a few plants are eaten by people in some parts of North America. Animals like the deer also feed on it, and birds such as warblers and hummingbirds use its soft parts to line their nests. In Hawaii, cushions and mattresses are stuffed with tree ferns. In Europe, bracken is used as thatching (covering) for roofs and also as bedding for cattle.

Finally, ferns such as the common polypody and spleenworts contribute to the building of fresh soil. These ferns grow out of cracks in rocks and help to break up the rocks over long periods of time. Eventually the rock is turned into fresh layers of soil. Ferns also become rich fertilizer for soil when their leaves decay.

Not all ferns are useful; some are pests to humans. They often block water from being carried into rice paddies by growing over irrigation ditches. Ferns also kill plants and fish in lakes by growing on water surfaces. This prevents light and oxygen from reaching the life forms under the water.