Life with Little Water

Questions & Prompts

• Dive into the photograph and imagine you are standing in the photograph. What do you see? What do you smell? What do you hear? What do you taste? What do you feel?

• Plants need air, nutrients, sunlight, and water. Which of these can you identify in the photograph? Which can you not see?

• What plant adaptations can you identify in these photographs?

• What questions do you have?

In dry, hot, sunny environments, water is often a limiting factor. Adaptations to limited water availability include:

Succulence. Succulent stems and leaves are thick because they are full of water. Succulent plants often have squishy leaves or stems because the organ is filled with liquid! Sometimes the leaves and stems are not squishy because the organs are tough and full of fiber. Succulence is when a plant stores water in its leaves or stems. When it is very dry in the plant's environment, this plant can use its stored water to help it stay alive. Succulence is an adaptation to help the plant survive in hot and dry environments.

Small Leaf Size or No Leaves. Small leaves take less energy to keep alive than large leaves. Leaves are covered in stomas. Stomas release water into the environment when they open. Plants living in places with very little water need to save as much water as they can, and this adaptation helps with that! Small leaves have fewer stomas so they release less water. Small leaves and no leaves are an adaptation to help the plant survive in hot and dry environments.

Vertical Leaves and Stems. The vertical leaves and branches help the plant stay cool. Overheating is dangerous for people, and it is dangerous for plants too! Vertical leaves and branches are an adaptation to minimize the parts of the plant facing the sun during the hottest part of the day. The shade produced by the leaves and stems helps the plant keep its water longer. Vertical leaves and stems are an adaptation to help the plant survive in hot and dry environments.

Pale Leaves and Stems. Pale leaves and stems reflect more sunlight than dark leaves. Pale leaves and stems absorb less heat than dark leaves and stems. This prevents overheating! Overheating is dangerous for people, and it is dangerous for plants too! Pale leaves and stems are an adaptation to help the plant survive in hot and dry environments.

Hairs. Hairs can trap moisture and increase the humidity (amount of water) around the surface of the leaf and stem. The surface of the leaf has stomas. Stomas release water into the environment when they open. Plants open their stomas more in dry environments and less in humid environments. By increasing the humidity around the stomas, the hairs help the stomas open less often. This adaptation helps the plant conserve water. White hairs also reflect the sunlight so the plant absorbs less heat. Hairs are an adaptation to help the plant survive in hot and dry environments.

Waxy Surfaces. All leaves have a cuticle that protects the leaf and helps to keep water inside. Some stems also have a waxy covering on the outside. Some plants have adapted an especially thick waxy cuticle. When the cuticle is thick, the plant keeps even more water inside! Waxy cuticles are an adaptation to help the plant survive in hot and dry environments.

Deep Roots. Dry environments often have water stored deep underground. Some humans who live in these dry environments have adapted by building wells. Humans use wells to access the water from underground. Some plants have evolved a similar adaptation for accessing water from underground reserves. Deep tap roots! Deep tap roots are an adaptation to help the plant survive in hot and dry environments.

Shallow Spreading Roots. Rain is rare in deserts and other dry environments. When rain does fall, it evaporates quickly because the air is so hot. Plants that rely on rainwater in dry environments need to absorb the water as quickly as they can! Roots that are close to the surface can capture the rainwater before it evaporates. Roots that spread out in a wide area around the plant can capture rainwater from a wide area.

Similarities across the World

Look closely at these plants side-by-side. What similarities do you see? What differences?

These plants look so similar. We might expect them to be very closely related and to live in the same place. But that is not the case!

The Copiapoa has evolved for thousands of years in North and South America. The Euphorbia has evolved for thousands of years in Africa. Why do they look so similar?

Plants evolve adaptations that help them survive their environments. When environments are similar, plants adapt similar strategies for success. In the case of these plants, the conditions in the Americas and in Africa led to very similar adaptations. When plants from different places evolve similar traits, this is called convergent evolution. Convergent means coming together.

Historical connection!

The Huntington’s library archives have many interesting documents from history. In the archives, we can find photographs of deserts! These photographs were taken over one hundred years ago by a man documenting Indigenous peoples of the Southwest United States and the places they lived (and still live today).

Look at the photos below. What do you notice?

Questions & Prompts

• If you could visit one of the deserts in these photographs, which desert would you visit? Why?

• Dive into the photograph. Choose one of the photos and imagine you are standing in the photograph. What do you see? What do you smell? What do you hear? What do you taste? What do you feel?

• What do each of the three deserts in the photos have in common?

• How do the three deserts look different?

• Plants need air, nutrients, sunlight, and water. Which of these can you identify in the photographs? Which can you not see?

• What plant adaptations can you identify in these photographs?

• What questions do you have?

Explore desert conservation!

• Some desert plants have adapted to areas with little rain by developing deep taproots [link: roots] that draw up water from underground. Private companies have tried for decades to build a pipeline to move this groundwater from the desert to urban areas in Southern California (like Los Angeles). Removing the water from the desert would take the water away from plants and animals who need it for survival. Learn more about the conservation efforts to save the desert groundwater for the plants and animals here.

• Farmers in the Atacama Desert have developed a sustainable technology for gathering water: catching clouds!