Transpiration

Transpiration is the process through which water is carried from roots to leaves in a plant.
It’s an important segment of the water cycle and is essentially a type of evaporation from plants.
Transpiration happens in the stomata - small pores present in the leaves of a plant.

The stomata are small pores on the leaf surface which open and close to facilitate transpiration.
They are surrounded by two guard cells which control the size of the stomatal opening.
The opening of the stomata allows for gas exchange - necessary for photosynthesis.
However, it also leads to loss of water from the plant through transpiration.

Water is absorbed by the roots from the soil and travels through the xylem vessels to reach the leaves.
In the leaf cells, water evaporates into the air spaces present in the spongy mesophyll tissue.
When the stomata open for gas exchange, this water vapour is lost to the surrounding air, in a process known as transpiration.
The transpiration process creates a transpirational pull, a tension that ‘pulls’ more water up from the roots.

Several factors can influence the rate of transpiration, these include: temperature, light intensity, wind speed, and humidity.
A higher temperature speeds up evaporation and thus increases the rate of transpiration.
More light causes the stomata to open wider, enabling more transpiration.
Greater wind speed can carry away the humid air surrounding the leaf, enhancing transpiration.
Decreased humidity in the air around a plant can also speed up the rate of transpiration.

Transpiration is vital for the transport of water and minerals throughout the plant.
It assists with temperature regulation, as the evaporation of water cools the plant down.
The water movement driven by transpiration helps in providing the plant with its turgidity, maintaining structural rigidity.
Transpiration also helps with the uptake of water from the soil as the process creates a suction force in the roots.