A seed is a baby plant with a coat around it. A seed can wait, doing nothing, until the conditions are right. Then a dry seed soaks up water and swells. The first root comes out of the seed coat. After the root, a shoot grows up with the leaves and the stem.

Water is not all a seed needs. It also needs air with oxygen in it, and soil soaked with water can leave a seed with too little oxygen. Most vegetable seeds sprout best in soil that is about 65 to 75 degrees Fahrenheit. Apple seeds will not sprout unless they have a cold spell first.

Once the plant is up, its roots go to work. Roots hold a plant in the ground and take in water. Then the plant lets water vapor go from its leaves into the air. This is called transpiration. The plant takes up liquid water from the soil and sends vapor into the sky.

A plant also makes its own food. This is called photosynthesis. The plant uses sunlight, water and carbon dioxide. A stem holds the leaves up so they can reach the sunlight. Plants look green because of chlorophyll, which takes in blue and red light.

Photosynthesis makes sugar for the plant. It also gives off oxygen, which people and animals breathe. People and animals breathe that oxygen.

Flowers are how plants make seeds. Pollination is moving pollen from the anther of a flower to the stigma. Many plants need bees, butterflies, birds, bats and other animals to carry pollen from flower to flower. A bee gets pollen stuck to its body while it drinks nectar. Wind can carry pollen too. After pollination, the ovule inside a flower becomes the seed and the ovary becomes the fruit.

Seeds need a way to travel. Some have wings or fluff, so the wind can carry them away, like maple and dandelion seeds. Burrs have little hooks that stick to animal fur, so animals carry the seeds away. A coconut is a seed that floats, and it can drift across the ocean and grow in a new place.

Some plants grow very big. Coast redwoods are the tallest trees on Earth, about 380 feet tall. As of November 2026, the tallest one known is 379 feet. Giant sequoias can live for more than three thousand years. Each one starts as a seed about the size of a grain of oatmeal.

Words to know

• pollination: moving pollen
• chlorophyll: green plant stuff
• transpiration: plant water loss
• oxygen: gas we breathe

The short version

A seed holds a tiny baby plant inside a protective coat. With water, warmth and oxygen it swells, its first root comes out, and then a shoot with leaves and a stem grows up. Leaves use sunlight, water and carbon dioxide to make sugar, which is called photosynthesis, and they give off oxygen.

Quick facts

• A seed needs water, oxygen and warmth; most vegetable seeds sprout best in soil that is about 65 to 75 degrees Fahrenheit.
• Photosynthesis uses sunlight, water and carbon dioxide to make sugar, and it gives off oxygen.
• Pollination moves pollen from the anther of a flower to the stigma, and bees, butterflies, birds and bats help.
• A giant sequoia starts as a seed about the size of a grain of oatmeal.