A seed is a baby plant with a coat around it. It can wait, doing nothing, until the conditions are right. Then a dry seed soaks up water and swells. 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.

When a seed sprouts, its first root comes out of the seed coat first; after the root, a shoot grows up with the leaves and the stem. Roots hold a plant in the ground and take in water. A fungus can help. Fungi can join with a tree's roots and, in return for sugar, give the tree minerals and water.

In photosynthesis, a plant uses sunlight, water and carbon dioxide to make its own food. 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. The process makes sugar for the plant and gives off oxygen, which people and animals breathe.

Leaves take in carbon dioxide and give off oxygen through tiny openings called stomata, and water vapor leaves through them too. Plants take up liquid water from the soil and let water vapor go from their leaves into the air. This is called transpiration.

Flowers are how plants make seeds. Pollination is moving pollen from the anther of a flower to the stigma, and 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 when it lands on a flower and drinks nectar. Then it carries the pollen to the next flower. Wind can carry pollen too. After pollination, the ovule inside a flower becomes the seed and the ovary becomes the fruit.

Seeds must also get away from the parent plant. 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 seeds grow into giants. Coast redwoods are the tallest trees on Earth, about 380 feet tall, and as of November 2026 the tallest one known is 379 feet. A giant sequoia starts as a seed about the size of a grain of oatmeal. Yet it can live for more than three thousand years.

Words to know

• transpiration: plant water loss
• stomata: tiny leaf holes
• chlorophyll: green plant stuff
• fungi: mushroom-type living things