Transpiration

Lesson

Part 1 — how plants lose water vapour, how stomata open and close, and how we show it.

In this lesson you will

Concept

What is transpiration?

Transpiration is the loss of water as vapour from the aerial parts of a plant.

Table of three routes of transpiration: stomata lose most, the cuticle a small amount and lenticels very little
Route	Share of water lost
Stomata (stomatal transpiration)	Most of it
Cuticle (cuticular)	A small amount
Lenticels in bark (lenticular)	Very little

Concept

Table of the effects of transpiration and how each helps or harms the plant
Effect	How it helps the plant
Transpiration pull	Draws water and minerals up the xylem from the roots
Cooling	Evaporation takes away heat from the leaves
Distribution	Carries minerals to all parts of the shoot
Water loss	Can cause wilting if loss exceeds uptake: a necessary evil