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

Plants also take up water from the ground and release it through transpiration from their leaves.

From Popular-Science

Instead, their leaves quickly cover walls and begin the work of transpiration.

From Science News For Students

First, the National Highway Transpiration Safety Administration (NHTSA) came down as hard as it could Friday on General Motors.

From The Daily Beast

His book begins with the research for which he is best known, namely that on transpiration.

From Project Gutenberg

Small passages should likewise be left throughout the body of the work, for the transpiration of moisture.

From Project Gutenberg

The remedy for this is to spray the leaves frequently so as to keep the air about them moist and so check transpiration.

From Project Gutenberg

Warm dry air, especially when in motion, promotes the aeriform transpiration, by favouring evaporation.

From Project Gutenberg

These are,—the expired air, or the secretion of the air-cells of the lungs,—and the ordinary cutaneous transpiration.

From Project Gutenberg

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