Many plants found in the desert have a thick cuticle and only open their stomata at night. Why might these two adaptations be useful for desert plants?

To reduce the rate of transpiration.

Explanation:

Transpiration can be explained as situation whereby water escape or evaporate from the plant through the pore that are present on the surface of the leaves or stems.

It should be understood that desert is a place that have a little amount of water due to high temperature of the environment and low rainfall. This means that the plants that must survive in that kind of area must develop adaptive features that will drastically reduce the rate at which water will be lost.

This is what results to the formation of thick cuticle, which can also be referred to as thick waxy cuticle. This help to reduce heat, because the wax on the leaves or stems will reflect heat thus lower temperature. Also it reduces the rate of evaporation.

Stomata are the holes in plant leaves through which they  transpire water. The desert plants  have very  small stomata and fewer stomata than those of

other plants, which also lie deep in the plants' tissues and only open in the night when the rate of transpiration is low.

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.