What is a Root?
Roots are one of the three organs of a plant. The primary function (most important job) of the roots is to take in water and nutrients. Just like people, plants need water and nutrients to grow! Roots also anchor the plant, and help the plant survive periods with too much or too little water and nutrients.
One of the roots’ most important jobs is to help the plant stay in one place.
While most roots grow from other roots underground, some get their start by growing out of stems above the ground. These roots grow down into the ground and become prop roots. Prop roots help to keep the plant upright. Many ficus trees (like this one!) have prop roots.
Taking in Water and Nutrients
Where do you get your food and water? Some places people get their food and water are the grocery store, at the community food bank, at a restaurant, and in our school lunches. These are all great places for people to get food, but plants can’t go to these places! Plants need to get all of their water and nutrients from their surroundings.
Some plants have a taproot, which is a single main root that grows deep down. Smaller roots can grow out of the taproot. Other plants have fibrous roots that branch out underground forming a dense network. Roots can be strong enough to break rocks, but their delicate tips absorb water as well as dissolved minerals and nutrients. This mixture of water, minerals, and nutrients travels up into plants to support the growth of their stems and leaves.
Coping with Shortage and Surplus
When we get hungry, we try to find food. Sometimes we get our food from our refrigerator or cupboards. Our cupboards and refrigerators help us store food that we can eat later when we are hungry. The food we find and eat helps us survive and grow.
Plants don’t have refrigerators or cupboards! They need another way to store food for later. Roots can store food, water, or both. Carrots, beets, and sweet potatoes are familiar roots that store food for growth spurts. When we eat carrots, beets, sweet potatoes, and other root vegetables, we are eating the nutrients and water the plant was storing!
Use the interactive image below to explore the life of a caudiciform (food-storing) radish root!
The Life of Radish
Use this interactive image to explore the changes to the radish root throughout its life.
Germination- Inside each radish seed, there is a tiny root called a radicle. In germination, the primary root descends into the earth.
Growing downward- The taproot grows downward and other roots branch off. The root tip on each of these roots absorbs nutrients.
Photosynthesis- The leaves are above ground and are starting to photosynthesize. The plant now has access to the sugar it makes from sunlight.
Storage in the root- The plant uses some of these sugars to help it grow bigger, and stores the extra sugars in the root.
The fattening of the root- The root gets fatter and juicier as more and more water, sugar, and nutrients get stored in the root.
Maximal juiciness- If we were harvesting this radish for food, we would want to pull it up from the ground at this stage. This stage is when the root has stored as much sugar, water, and nutrients as it is going to.
Using the stored resources- Growing flowers and fruit takes a lot of energy! The radish transports sugar, water, and nutrients up the stem to help the plant grow the flowers it needs for reproduction.
All used up- Now that the radish has shot its stem upward and grown flowers, its root is tough. The root still draws in nutrients and it still anchors the plant in the earth, but it no longer stores extra sugar, water, and nutrients for the plant.