epiphyte(redirected from Air-plants)
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air plant,any plant that does not normally root in the soil but grows upon another living plant while remaining independent of it except for support (thus differing from a parasiteparasite,
plant or animal that at some stage of its existence obtains its nourishment from another living organism called the host. Parasites may or may not harm the host, but they never benefit it.
..... Click the link for more information. ). An epiphyte manufactures its own food (see photosynthesisphotosynthesis
, process in which green plants, algae, and cyanobacteria utilize the energy of sunlight to manufacture carbohydrates from carbon dioxide and water in the presence of chlorophyll. Some of the plants that lack chlorophyll, e.g.
..... Click the link for more information. ) in the same way that other green plants do, but obtains its moisture from the air or from moisture-laden pockets of the host plant, rather than from the soil. Some epiphytes are found in every major group of the plant kingdom. Of the flowering plants, the best-known epiphytes are orchids and bromeliads, such as Spanish moss. Epiphytes may grow upon the trunk, branches, or leaves of the host plant, sometimes so thickly as to damage the original plant by crowding out its leaves. They are most abundant in the moist tropics.
a plant that grows on other plants, mainly on the branches and trunks of trees. (Epiphytes that grow on the leaves of other plants are called epiphylls.) Epiphytes, unlike parasites, obtain their nutritive substances from the environment and not from the host plant.
Epiphytes exist in all classes of plants. They occur in the greatest numbers in moist, warm regions, especially in tropical forests, where both lower and higher epiphytes are found (mainly from the families Orchidaceae and Bromeliaceae). There is an abundance of epiphytes in moist, less warm regions, including mountainous areas, where they are represented primarily by mosses, lichens, and ferns. The predominant epiphytes in damp cold regions are mosses, lichens, and aquatics. Semi-epiphytes (many Araceae, banyan, and others) begin their development on trees and then form long hanging adventitious roots that penetrate the ground for water and mineral substances.
During the evolutionary process, true epiphytes have developed adaptations for catching water and mineral substances from the air. These adaptations include spongy covers on the roots and root pockets—that is, roots woven together to form baskets in which dust and fallen leaves accumulate. Soil is thus produced for the feeding roots (for example, Asplenium and Grammatophyllum). Some epiphytes have recessed leaves that form a niche on the stalk in which soil is accumulated (for example, Platycerium). In some Bromeliaceae the leaves form a cone in which water accumulates; the water is then sucked up by hairs on the inner surfaces of the leaves.
Many epiphytes have developed adaptations to economize on water consumption. The adaptations, similar to those in xerophytes, include the development of dense leaves with a thick cuticle, a reduction in leaves, the formation of special compartments for water storage, and the appearance of a pubescence on the leaves.
Epiphytes developed during the evolutionary process apparently in connection with the special ecological conditions in shady, damp places, moving from the dark lower tiers of forests toward the light on the branches of trees. Early epiphytes probably had small, lightweight seeds and spores that could be disseminated even by the slightest air currents.
REFERENCESPoplavskaia, G. I. Ekologiia raslenii, 2nd ed. Moscow, 1948.
Alekhin, V. V. Geografiia rastenii, 3rded. Moscow, 1950.
Schmidthüsen, J. Obshchaia geografiia rastitel’nosti. Moscow, 1966. (Translated from German.)
Walter, H. Rastitel’nost’ zemnogo shara, vol. 1. Moscow, 1968. (Translated from German.)
N. I. SHORINA