Answer:
To reduce the rate of water loss from plants widely known as TRANSPIRATION
Explanation:
Transpiration is the loss of water by evaporation in terrestrial plants, especially through the stomata; accompanied by a corresponding uptake from the roots.
Desert plants are adapted to their arid
environment in many diff erent ways. Stomata
are the holes in plant leaves through which they
transpire water. Many desert plants have very
small stomata and fewer stomata than those of
other plants. The stomata of many cacti lie deep
in the plants’ tissues. This adaptation helps cacti
reduce water loss by keeping the hot, dry wind
from blowing directly across the stomata.
The leaves and stems of many desert plants have
a thick, waxy covering. This waxy substance
does not cover the stomata, but it covers most
of the leaves, keeping the plants cooler and
reducing evaporative loss.
Small leaves on desert plants also help reduce
moisture loss during transpiration. Small leaves
mean less evaporative surface per leaf. In
addition, a small leaf in the sun doesn’t reach as
high a temperature as a large leaf in the sun.
Some plants, such as Mormon tea and cacti,
carry out most or all of their photosynthesis
in their green stems. (Cactus pads are stems,
botanically speaking.) Some desert plants grow
leaves during the rainy season and then shed
them when it becomes dry again. These plants,
including blackbrush, photosynthesize in their
leaves during wet periods. When drought sets
in and the plants lose their leaves, some of
these plants can photosynthesize in their stems.Others cut down on water loss even further by
temporarily shutting down photosynthesis.
Other desert adaptations shared by a number
of plants include shallow widespread roots to
absorb a maximum of rainfall moisture and
spines or hairs to shade plants and break up
drying winds across the leaf surface.
