Food from Sunlight

Plants can do an amazing thing: They make their own food using just water, sunlight, and carbon dioxide. This process is called photosynthesis. They capture the energy from the sun and use it to convert water and carbon dioxide into carbohydrates (sugars). Plants then use the carbohydrates to grow. 

Plants (and a few other lifeforms) release oxygen during photosynthesis. This is lucky for us since all animals (including humans) need oxygen to survive! Humans can survive on this planet because plants release oxygen. Zoom in on the poster below to learn more about the process of photosynthesis.

Photosynthesizing Leaves

On most plants, leaves are the organ responsible for photosynthesis. All of these plants have leaves that photosynthesize, but the leaves look very different!   

Questions & Prompts 

• Imagine what it would feel like to touch these leaves. Which one would be more pleasant to touch? Why?
• Use the color cards to match these leaves to a color. What can this color tell you about the plant’s environment?
• Look closely at the leaf shapes. Which leaf do you think absorbs more sunlight? Why?
• What sort of environment do you think each of these plants lives in? Create an artwork or write a descriptive paragraph of each environment to help others understand your thinking. 

All plants need sunlight, water, and air for photosynthesis.  

Adaptations to a Lot of Light

Plants need sunlight to make food, but too much sunlight can be a problem. Overheating is dangerous for people, and it is dangerous for plants too! Plants that live in hot, sunny environments have access to more sunlight than they need.

Adaptations to a lot of light include: 

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 reflect more sunlight than dark leaves. Pale leaves absorb less heat than dark leaves. This prevents overheating! Overheating is dangerous for people, and it is dangerous for plants too! Pale leaves 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.

Adaptations to Limited Light

Sometimes sunlight is a limiting factor for plants. This means the plant does not have easy access to sunlight because it lives in a shady environment.  Limited light can be a difficulty for plants who need sunlight for photosynthesis! 

Adaptations to limited light include: 

Large, Wide Leaves. In wet conditions, many plants grow close together. When plants are crowded, it can be hard for them to get enough sunlight! Large leaves have a better chance of absorbing the available light. The plant needs that light to create food! Large, wide leaves are an adaptation to help the plant make food while in a shady environment. 

Dark Green Leaves. Dark leaves absorb more light than pale leaves. Dark leaves help plants that live in shady environments absorb as much sunlight as they can! Dark green leaves are an adaptation to help the plant make food while in a shady environment. 

Horizontal Leaves. Horizontal leaves expose as much of the leaf surface as possible to the sun. This adaptation helps plants capture any available sunlight. Horizontal leaves are an adaptation to help the plant make food while in a shady environment. 

Exceptional Photosynthesizers

On most plants, leaves are the organ responsible for photosynthesis, but not on all plants!