My Science School

If a seed grew close to its parent, it probably would be in the shade. It could not get the sunlight it needs to grow. It would not have enough space to grow, either. Somehow, the seed must get to a place where it can grow. Luckily, seeds have many ways of doing this.

Some seeds, such as those of the maple tree, float on the wind. Their “wings” carry them a long way. Other seeds catch a ride with animals. When animals eat fruit, they eat the seeds along with it, and the seeds pass through the animal’s body. The animal may travel far before dropping the seeds. Other seeds, such as those of bur marigolds and cleavers, grow inside fruits that stick to things. They hitchhike on the fur of passing animals until they are brushed off.

Some fruits actually explode. Dry peapods split open, hurling their seeds in all directions. Touch-me-not plants have pods that fly open at the slightest movement. And the squirting cucumber shoots out seeds in a jet of liquid.

Plants have many different parts. Many have roots, stems, and leaves. All the parts work together to help the plant live and grow. Not every plant has all these parts, but most do.

Roots grow from the bottom of the plant down into the ground and spread out. Like sponges, roots soak up water and minerals for the plant. Roots are anchors too. By growing down and spreading out in the ground, they hold a plant firmly in place.

Stems support a plant’s leaves and hold them towards the light. Flowers grow from the stems. Water and minerals travel to the rest of the plant through tiny tubes in the stems. The trunk of a tree is a big stem.

Leaves make food for the plant. They use the energy of sunlight to change air, water, and minerals into sugar and starch. Leaves grow in many shapes and sizes. Some are broad and flat. Others are long and thin. Some leaves have smooth edges. The edges of other leaves are jagged or wavy. And some leaves look like needles or spines.

Picture Credit : Google

Leaves don’t seem to do anything at all. But if you could become tiny enough to peek inside a leaf - you would have a surprise!

Sunlight comes into a leaf through the leaf’s skin. Inside, the leaves have a wonderful green substance called chlorophyll. The chlorophyll catches some of the sunlight that falls on the leaf. At the same time, air comes into the leaf through many tiny openings. And water moves up from the roots below.

Leaves are like little food factories. Using sunlight for energy, the chlorophyll changes water and a gas from the air into food for the plant.

Besides green, leaves have other colours, such as yellow and orange. In summer, the green chlorophyll covers the other colours. In the autumn, it sometimes fades. Then you see the other colours.

If someone asked you to name a plant, you might say, “a tree”. You’d probably think of many other green and leafy living things, too. But not all plants are green and leafy. Most are, but not all.

So what makes a plant a plant?

Plants usually spend their whole lives rooted to one place. They can’t move around like animals. Most plants produce seeds to make new plants.

Plants also have special kinds of cells. Plant cells have tough, thick walls made of cellulose. And most plants contain a special substance called chlorophyll. Plants use chlorophyll to make their own food with the help of water, air, and sunlight. Animals have no chlorophyll.

Picture Credit : Google

Plants are divided into groups.

Almost all plants belong to the group called seed plants. They’re called seed plants because they make seeds that grow into new plants.

Most seed plants are flowering plants. Flowering plants make their seeds inside flowers. By far, most plants in the world are flowering plants. Other seed plants make their seeds inside cones. Cone-bearing plants are called conifers. These plants include such trees as pines, spruces, and firs. Plants called cycads and ginkgoes (also called maidenhair trees) also are cone-bearing plants. These types of plants have been around for millions of years.

Other plant groups use tiny cells called spores, not seeds, to make new plants. Spore-making plants include ferns, horsetails, and mosses.

Ferns have feathery leaves called fronds. Their spores form on the undersides of the fronds. Horsetails have tall, green stems with a cap on top. They have long, thin leaves. Moss grows like a soft, green furry coat on a tree trunk or a rock. Moss is made up of thousands of tiny plants growing very close together.

Picture Credit : Google