ferns are mostly found in dry climate? (true or false)
Answers
Answer:
false
Explanation:
Fern, (class Polypodiopsida), class of nonflowering vascular plants that possess true roots, stems, and complex leaves and that reproduce by spores. The number of known extant fern species is about 10,500, but estimates have ranged as high as 15,000, the number varying because certain groups are as yet poorly studied and because new species are still being found in unexplored tropical areas. The ferns constitute an ancient division of vascular plants, some of them as old as the Carboniferous Period (beginning about 358.9 million years ago) and perhaps older. Their type of life cycle, dependent upon spores for dispersal, long preceded the seed-plant life cycle. Another informal name for the group, monilophytes, has gained currency in modern botanical literature.
tree fern
tree fern
Tree fern (Cyathea medullaris).
Copyright John Shaw/Bruce Coleman Inc.
Fern
QUICK FACTS
KEY PEOPLE
Sir William Jackson Hooker
Frederick Orpen Bower
Douglas Houghton Campbell
RELATED TOPICS
Plant
Lower vascular plant
Pteridaceae
Tree fern
Mosquito fern
Hymenophyllaceae
Bracken
Water fern
Polypodiaceae
Ophioglossaceae
General Features
Size range and habitat
The ferns are extremely diverse in habitat, form, and reproductive methods. In size alone they range from minute filmy plants only 1–1.2 cm (0.39–0.47 inch) tall to huge tree ferns 10 to 25 metres (30 to 80 feet) in height. Some are twining and vinelike; others float on the surface of ponds. The majority of ferns inhabit warm, damp areas of the Earth. Growing profusely in tropical areas, ferns diminish in number with increasingly higher latitudes and decreasing supplies of moisture. Few are found in dry, cold places.
filmy fern
filmy fern
Filmy fern (Trichomanes).
Copyright Fletcher & Baylis/Photo Researchers
Observe how the sporophytic fern appears to unfurl upward as it grows from its rhizome
Observe how the sporophytic fern appears to unfurl upward as it grows from its rhizome
Time-lapse photography of fern growth.
Encyclopædia Britannica, Inc.
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Some ferns play a role in ecological succession, growing from the crevices of bare rock exposures and in open bogs and marshes prior to the advent of forest vegetation. The best-known fern genus over much of the world, Pteridium (bracken) is characteristically found in old fields or cleared forests, where in most places it is often succeeded by woody vegetation.
Distribution and abundance
Geographically, ferns are most abundant in the tropics. Arctic and Antarctic regions possess few species. On the other hand, a small tropical country such as Costa Rica may have more than 900 species of ferns—about twice as many as are found in all of North America north of Mexico. The finest display of fern diversity is seen in the tropical rainforests, where in only a few hectares more than 100 species may be encountered, some of which may constitute a dominant element of the vegetation. Also, many of the species grow as epiphytes upon the trunks and branches of trees. A number of families are almost exclusively tropical (e.g., Marattiaceae, Gleicheniaceae, Schizaeaceae, Cyatheaceae, Blechnaceae, and Davalliaceae). Most of the other families occur in both the tropics and the temperate zones. Only certain genera are primarily temperate and Arctic (e.g., Athyrium, Cystopteris, Dryopteris, and Polystichum), and even these tend to extend into the tropics, being found at high elevations on mountain ranges and volcanoes.
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Ferns are uncommon as invasive species outside of their native ranges, although a few occur. The most notorious is bracken (Pteridium), which spreads quickly by its underground ropelike rhizome, rapidly invading abandoned fields and pastures in both temperate and tropical regions. One species of water spangles (Salvinia auriculata) became a major pest in India, blocking irrigation ditches and rice paddies. Another species (S. molesta) within three years covered 520 square kilometres (200 square miles) of the artificial Lake Kariba in southern Africa, cutting off light and oxygen and thus killing other plant life and fish. Some fern species have been introduced into tropical or subtropical areas (e.g., southern Florida and Hawaii) and in some cases have become naturalized and have spread into the native forest. Examples include the giant polypody (Microsorum scolopendrium), climbing ferns (Lygodium japonicum and L. microphyllum), green cliff brake (Cheilanthes viridis), silver fern (Pityrogramma calomelanos), Japanese holly fern (Cyrtomium falcatum), rosy maidenhair (Adiantum hispidulum), Cretan brake (Pteris cretica), and ladder brake (P. vittata). Two Old World species (Cyclosorus dentatus and Macrothelypteris torresiana) were introduced into tropical America beginning about 1930 and now are among the most common species even in some remote are
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