transpiration

American  

[tran-spuh-rey-shuhn] / ˌtræn spəˈreɪ ʃən /

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.

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transpiration Scientific  

/ 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.

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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.

Etymology

Origin of transpiration

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

Compare meaning

How does transpiration compare to similar and commonly confused words? Explore the most common comparisons:

• transpiration vs. evaporation

Explanation

Plants breathe through their stomata, little openings that allow transpiration, which is the outward passage of water vapor along with carbon dioxide. This vapor then evaporates into the air as part of the process of photosynthesis. We can see the history of the word transpiration when we break it down into trans, a Latin noun which means "across," and spiration, which comes from the Latin verb spīrāre, meaning "to breathe." The tion suffix adds the meaning "the act of," so we can see transpiration is, literally, "the act of breathing across," which clearly identifies vapor emission from plant leaves. Transpiration is vital to the earth’s ecology, and is being reduced by our decimation of the forests.

Example Sentences

As carbon dioxide levels in the atmosphere increase, plants may need to open their stomata less frequently, leading to decreased transpiration and preserving more groundwater.

From Los Angeles Times • Dec. 20, 2024

As the air becomes hotter, it becomes easier for plants to lose water to transpiration, especially because photosynthesis occurs during daylight hours when temperatures are highest.

From Los Angeles Times • Dec. 20, 2024

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 • Apr. 30, 2024

These weren't within the scope of Boser's model, which only considers transpiration by the crops themselves.

From Science Daily • Mar. 25, 2024

With the cutting off of the water supply at the roots in late fall, transpiration is also cut off.

From Trees Worth Knowing by Rogers, Julia Ellen

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