The Three Sisters: An Ancient Ecosystem of Plants

Contributor: Stefani Allegretti. Lesson ID: 13385

Did you know that plants can actually help each other grow? Learn about a unique and ancient plant ecosystem first discovered by Native Americans called the Three Sisters. Then, plan your own garden!


Life Science, World Cultures

learning style
Auditory, Visual
personality style
Beaver, Golden Retriever
Grade Level
Middle School (6-8)
Lesson Type
Quick Query

Lesson Plan - Get It!

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Just like all living things, plants need certain things to grow.

Of course they need the basics such as sunlight, water, carbon dioxide, and nutrients. However, there are other factors that can influence how plants grow.

Keep reading to learn about a unique and ancient way of growing plants, first discovered by Native Americans (the Iroquois) long ago, called the Three Sisters.

Three Sisters ecosystem

  • What exactly are the Three Sisters?

The Three Sisters plants comprise corn plants, bean plants, and squash plants.

These plants, of course, have the same life cycle as any other plant. Their cycle of life includes pollination, reproduction, seed, germination, and growth:

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However, when these three specific plants are grown together, they create a unique ecosystem.

An ecosystem is a community of living organisms that interact with each other and their environment. In other words, they help each other grow!

Let's start with the bean (legume) plant.

pea plants

The bean plant takes nitrogen from the soil and air and makes it usable for the other plants.

The nutrient nitrogen (N) is a very important one for plants because it makes up part of the compound needed by plants to engage in the process of photosynthesis, called chlorophyll. Chlorophyll is essential for plants to live and grow.

Discover more about how bean plants help to fix nitrogen in Biological Nitrogen Fixation by Legumes from Sarah Haines:

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In addition to creating the compound corn and squash need to grow, the bean plant vines grow around the corn plant and help keep it sturdy.

  • What does the squash plant do in this unique trio?

butternut squash

The squash plant is the protector of the Three Sisters.

  • Can you guess why?

Look at how large the squash plant's leaves are. These help to keep the soil shaded from the sun, which in turn keeps it cool and moist. They also help prevent weeds from growing.

  • Have you ever picked up a pumpkin (a type of squash) and felt the prickly stem?


Squash plants are spiky, which helps keep animals away from it and the corn and bean plants.

On to the last plant in the trio: corn.

  • How does corn help?

Corn provides the vine-like bean plants with a place to climb.

Look at this example of the Three Sisters growing together:

corn, beans, and squash growing together

Image by Perry Quan, via Flickr, is licensed under the CC BY-SA 2.0 license.

  • Can you spot the bean vines around the corn and the squash leaves?

Review the Three Sisters planting system created by the Native Americans in this portion of How the Iroqouis Planted Corn from Good and Basic:

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Now, head on over to the Got It? section and test your knowledge about the unique ecosystem created by the Three Sisters!

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