Uses
Ferns are not as important economically as seed plants but have considerable importance in some societies. Some ferns are used for food, including the fiddleheads of bracken, Pteridium aquilinum, ostrich fern, Matteuccia struthiopteris, and cinnamon fern, Osmundastrum cinnamomeum. Diplazium esculentum is also used by some tropical peoples as food. Tubers from the King Fern or para (Ptisana salicina) are a traditional food in New Zealand and the South Pacific. Fern tubers were used for food 30,000 years ago in Europe. Fern tubers were used by the Guanches to make gofio in the Canary Islands. Ferns are generally not known to be poisonous to humans. Licorice fern rhizomes were chewed by the natives of the Pacific Northwest for their flavor.
Ferns of the genus Azolla are very small, floating plants that do not resemble ferns. Called mosquito fern, they are used as a biological fertilizer in the rice paddies of southeast Asia, taking advantage of their ability to fix nitrogen from the air into compounds that can then be used by other plants.
Many ferns are grown in horticulture as landscape plants, for cut foliage and as houseplants, especially the Boston fern (Nephrolepis exaltata) and other members of the genus Nephrolepis. The Bird's Nest Fern (Asplenium nidus) is also popular, as is the staghorn ferns (genus Platycerium). Perennial (also known as hardy) ferns planted in gardens in the northern hemisphere also have a considerable following.
Several ferns are noxious weeds or invasive species, including Japanese climbing fern (Lygodium japonicum), mosquito fern and sensitive fern (Onoclea sensibilis). Giant water fern (Salvinia molesta) is one of the world's worst aquatic weeds. The important fossil fuel coal consists of the remains of primitive plants, including ferns.
Ferns have been studied and found to be useful in the removal of heavy metals, especially arsenic, from the soil. Other ferns with some economic significance include:
- Dryopteris filix-mas (male fern), used as a vermifuge, and formerly in the US Pharmacopeia; also, this fern accidentally sprouting in a bottle resulted in Nathaniel Bagshaw Ward's 1829 invention of the terrarium or Wardian case
- Rumohra adiantiformis (floral fern), extensively used in the florist trade
- Microsorum pteropus (Java fern), one of the most popular freshwater aquarium plants.
- Osmunda regalis (royal fern) and Osmunda cinnamomea (cinnamon fern), the root fiber being used horticulturally; the fiddleheads of O. cinnamomea are also used as a cooked vegetable
- Matteuccia struthiopteris (ostrich fern), the fiddleheads used as a cooked vegetable in North America
- Pteridium aquilinum or Pteridium esculentum (bracken), the fiddleheads used as a cooked vegetable in Japan and are believed to be responsible for the high rate of stomach cancer in Japan. It is also one of the world's most important agricultural weeds, especially in the British highlands, and often poisons cattle and horses.
- Diplazium esculentum (vegetable fern), a source of food for some native societies
- Pteris vittata (brake fern), used to absorb arsenic from the soil
- Polypodium glycyrrhiza (licorice fern), roots chewed for their pleasant flavor
- Tree ferns, used as building material in some tropical areas
- Cyathea cooperi (Australian tree fern), an important invasive species in Hawaii
- Ceratopteris richardii, a model plant for teaching and research, often called C-fern
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