transpiration


transpiration
/tran'speuh ray"sheuhn/, n.
1. an action or instance of transpiring.
2. Bot. the passage of water through a plant from the roots through the vascular system to the atmosphere.
[1545-55; TRANS- + L spiration-, s. of spiratio breathing (spirat(us), ptp. of spirare to breathe + -ion- -ION); perh. directly < F or NL]

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Loss of water from a plant, mainly through the stomata (see stoma) of leaves.

Darkness, internal water deficit, and extremes of temperature tend to close stomata and decrease transpiration; illumination, ample water supply, and optimum temperature cause stomata to open and increase transpiration. Its exact significance is disputed; its roles in providing the energy to transport water in the plant and in aiding dissipation of the sun's heat (by cooling through evaporation of water) have been challenged. Since stomatal openings are necessary for the exchange of gases, transpiration has been considered by some to be merely an unavoidable phenomenon that accompanies the real functions of the stomata.

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botany
      in botany, a plant's loss of water, mainly through the stomates of leaves. Stomates consist of two guard cells that form a small pore on the surfaces of leaves. The guard cells control the opening and closing of the stomates in response to various environmental stimuli. Darkness, internal water deficit, and extremes of temperature tend to close stomates and decrease transpiration; illumination, ample water supply, and optimum temperature open stomates and increase transpiration. The exact significance of transpiration is disputed; its roles in providing the energy to transport water in the plant and in aiding in heat dissipation in direct sunlight (by cooling through evaporation of water) have been challenged. Stomatal openings are necessary to admit carbon dioxide to the leaf interior and to allow oxygen to escape during photosynthesis, hence transpiration has been considered by some authorities to be merely an unavoidable phenomenon that accompanies the real functions of the stomates.

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Universalium. 2010.

Look at other dictionaries:

  • transpiration — [ trɑ̃spirasjɔ̃ ] n. f. • 1503; lat. médiév. transpiratio 1 ♦ Excrétion de la sueur par les glandes sudoripares de la peau. ⇒ diaphorèse, moiteur, sudation; perspiration. Transpiration provoquée par la chaleur, l effort, l émotion. Diminution de… …   Encyclopédie Universelle

  • Transpiration — is the evaporation of water from the aerial parts of plants, especially leaves but also stems, flowers and roots. Leaf transpiration occurs through stomata, and can be thought of as a necessary cost associated with the opening of stomata to allow …   Wikipedia

  • Transpiration — Tran spi*ra tion, n. [F. transpiration.] 1. (Physiol.) The act or process of transpiring or excreting in the form of vapor; exhalation, as through the skin or other membranes of the body; as, pulmonary transpiration, or the excretion of aqueous… …   The Collaborative International Dictionary of English

  • transpiration — Transpiration. s. f. v. Mouvement des humeurs qui transpirent. Il faut faire de l exercice pour aider à la transpiration. il y a des maladies qui se guerissent par la seule transpiration …   Dictionnaire de l'Académie française

  • Transpiration — Transpiration, Wasserdampfabgabe über oberirdische Pflanzenteile bei Cormophyten; geschieht in erster Linie über die ⇒ Spaltöffnungen (stomatäre T.), zu einem geringen Teil auch über die ⇒ Cuticula (cuticuläre T.); ist wesentlicher Bereich des ⇒… …   Deutsch wörterbuch der biologie

  • Transpiration — (neulat.), Hautausdünstung, s. Ausdünstung; bei Gasen der Durchfluß durch kapillare Kanäle …   Meyers Großes Konversations-Lexikon

  • Transpiration — (neulat.), Hautausdünstung; transpirieren, ausdünsten, ausschwitzen …   Kleines Konversations-Lexikon

  • transpiration — index experience (encounter), happening Burton s Legal Thesaurus. William C. Burton. 2006 …   Law dictionary

  • Transpiration — Transpiration→Schweiß …   Das Wörterbuch der Synonyme

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  • transpiration — early 15c., from M.L. transpirationem, noun of action from transpirare (see TRANSPIRE (Cf. transpire)) …   Etymology dictionary


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