Transpiration

Transpiration is an important process within plants that occurs when water vapor leaves the plant through leaf stomata. The exit of water molecules through transpiration is responsible for the plant’s ability to pull water from its growth media up through its roots. Water’s cohesive property is responsible for this, since water molecules like to stick together; as molecules begin to evaporate through the stomata, the remaining molecules inside the plant’s vascular system are pulled upwards. This pull occurs all the way down the plant from the leaf to the root, where the plant can then pull more water up through its roots (see figure below).

Rendering of transpiration: water is absorbed by the plant through its roots. The water then travels up the plant’s stem, providing turgor to stabilize the plant and keep it upright. Water continues upwards to the leaves where it is used for photosynthesis and respiration. Excess water molecules are shed from the plant as water vapor, which evaporates through stomatal openings on the underside of the leaf.
Rendering of transpiration: water is absorbed by the plant through its roots. The water then travels up the plant’s stem, providing turgor to stabilize the plant and keep it upright. Water continues upwards to the leaves where it is used for photosynthesis and respiration. Excess water molecules are shed from the plant as water vapor, which evaporates through stomatal openings on the underside of the leaf.

Transpiration allows for the constant flow of water required by plants to perform photosynthesis and other growth processes, as well as providing turgor within the stems for the plant to stand upright and not wilt. Transpiration has a cooling effect on the plant in a similar way that sweating has on humans- heat held by water molecules leaves the plant as the molecules evaporate. Plant’s rate of transpiration can be modeled using mathematical equations, and used in data-driven growing as a growth factor.