What is Transpiration?
'''Transpiration''' is the [[evaporation]] of [[water]] from [[plant]]s, especially [[leaf|leaves]]. It is a type of [[translocation (botany)|translocation]] and part of the [[water cycle]]. The amount of water lost by a plant depends on its size, the light intensity, temperature, [[humidity]], [[wind speed]], and soil water supply. The process of '''Transpiration''' helps in regulating temperature in the plant. Transpiration was first worked out by [[Stephen Hales]] (17 September 1677 – 4 January 1761), an English [[clergyman]].<ref>Morton A.G. ''History of botanical science''. New York: Academic Press, 248{{ndash}}251.</ref><ref>Hales, Stephen 1727. ''Vegetable Staticks''. London: W & J Innys. [http://www.illustratedgarden.org/mobot/rarebooks/title.asp?relation=QK711H341727 {{Webarchive|url=https://web.archive.org/web/20070210020305/http://www.illustratedgarden.org/mobot/rarebooks/title.asp?relation=QK711H341727 |date=2007-02-10 }} <nowiki>[1]</nowiki>]</ref> He proved what is still believed, that the evaporation of water molecules from leaves is the main force pulling the water column up from its origin in the roots. == How transpiration works == [[Leaf]] surfaces are dotted with openings called [[stomata]], which act rather like [[pore (skin)|pores]]. In most plants there are more on the undersides of the leaves than on the top. The stomata are bordered by [[guard cell]]s that open and close the pore. Transpiration happens when the guard cells open the stomata. This lets [[oxygen]] and [[water vapour]] flow out, and [[carbon dioxide]] flow in. The carbon dioxide is used in [[photosynthesis]], and the oxygen is produced by photosynthesis. Transpiration also pulls water through the plant. This brings with it the mineral [[nutrients]] from [[root]]s to [[shoot]]s. Water moves out of the leaves into the [[atmosphere]]. This exerts a pull on the water column, which brings the water up against [[gravity]]. Water gets into the plant at the roots by [[osmosis]], and it transports dissolved mineral nutrients