transpiration

[ tran-spuh-rey-shuhn ]

noun

1. an action or instance of transpiring.
2. Botany. the passage of water through a plant from the roots through the vascular system to the atmosphere.

transpiration

/ trăn′spə-rā′shən /

1. The process of giving off vapor containing water and waste products, especially through the stomata on leaves or the pores of the skin.

Word History and Origins

Origin of transpiration¹

1545–55; trans- + Latin spīrātiōn-, stem of spīrātiō breathing ( spīrāt ( us ), past participle of spīrāre to breathe + -iōn- -ion ); perhaps directly < French or New Latin

A Closer Look

Plants need much more water than animals do. But why? Plants use water not only to carry nutrients throughout their tissues, but also to exchange gases with the air in the process known as transpiration. Air, which contains the carbon dioxide that plant cells need for photosynthesis, enters the plant mainly through the stomata (tiny holes under its leaves). The air travels through tiny spaces in the leaf tissue to the cells that conduct photosynthesis. These cells are coated with a thin layer of water. The cell walls do not permit gases to pass through them, but the carbon dioxide can move across the cell walls by dissolving in the water on their surface. The cells remove the carbon dioxide from the water and use the same water to carry out oxygen, the main waste product of photosynthesis. All this mixing of water and air in transpiration, though, has one drawback: more than 90 percent of the water that a plant's roots suck up is lost by evaporation through the stomata. This is why a plant always needs water and why plants that live in dry climates, such as cacti, have reduced leaf surfaces from which less water can escape.

Example Sentences

"We could exactly pinpoint how this is related to water transpiration and the ions the plant carries via the ascent of sap."

From Science Daily

ET includes evaporation from soil and open water pools such as lakes, rivers, and ponds, as well as transpiration from plant leaves.

From Science Daily

Scientists have a variety of methods to estimate the amount of water ascending from the Earth's surface to the atmosphere due to evaporation and transpiration through plant leaves.

From Science Daily

So, she compared transpiration in fallowed fields to active fields across the Central Valley.

From Science Daily

Ultimately, a full 10% of crop transpiration could be saved if the top 50% of water users reduced their water consumption to match that of their median-consuming neighbors.

From Science Daily

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