Plant Adaptations

What do plants need? Light Water Space Nutrients Warmth

Why do plants need water? Photosynthesis Support Transport

Transpiration Plants take in water from the roots and lose water from the leaves. Water moves up plants in the transpiration stream. Leaves have small holes called stomata to allow gases (oxygen and carbon dioxide) to enter and leave the leaves. Water vapour also escapes through the stomata.

Stomata The guard cells change shape to open and close the stomata. When conditions are dry the plant closes the stomata to reduce water loss

Rate of Transpiration Plants lose water more quickly in dry and hot conditions e.g. deserts. Plants that live in dry and hot conditions have adapted to reduce their water loss.

Reduced Leaf Surface Area A reduced surface area to volume ratio reduced water loss. Cacti have reduced their surface area by losing their leaves. Have spines instead. This also prevents animals from eating them.

Reduced Leaf Surface Area Marram grass which lives on sand dunes has reduced its surface area by having its leaves rolled inwards to trap a layer of moist air The stomata are on the inside here it is more moist and so less water is lost

Cross Section of Marram Grass

Root Systems Cacti often have very shallow roots that spread out widely. This means they can catch water as soon as it rains. Other plants may have very deep roots

Water Storage Some plants known as succulents store water inside fleshy stems leaves or roots

Other plant adaptations Some desert plants have broad leaves to catch the dew in the evenings. This is then funnelled into their root systems Some desert plants have fleshy leaves with a thick cuticle to prevent evaporation Some plants break down insect’s bodies to release minerals