Category Botany

Have you ever seen firefighters using a fire hose? The hose looks stiff and fat while water is running through it. But when the fire is put out and the firefighters turn off the water, the empty hose is limp.

Many plants are something like a fire hose. As long as their roots keep pumping water, their stems and leaves stand up straight and stiff. But a plant loses water through its leaves. If the plant doesn’t get enough water to replace the lost water, it will soon flop over, just like an empty fire hose. Perhaps you’ve seen this happen to potted plants. They begin to droop when they need water.

Plants that live in deserts, where there is very little water; have special ways of collecting and storing water. For example, the roots of some cactus plants grow down deep or spread out very far to find water. Cactus plants store the water in their thick, fleshy stems. When there is no rain, they live off the stored water. 

The kinds of trees that are often used as Christmas trees are called conifers or needleleaf trees. They are called needleleaf trees because their leaves are thin and sharp, like needles. Pines, spruces, and redwoods are all conifers.

Most conifers are green all year. They are called evergreens. They don’t change colour and lose all their leaves at a certain time each year as deciduous trees do. Instead, they lose a few needles at a time, all year round.

Conifer needles are very tough. They don’t freeze in winter, and they don’t lose water as quickly as other kinds of leaves do. By holding on to the water they have, conifers stay alive and green all winter.

Picture Credit : Google

Many broadleaf trees lose their leaves once a year and later grow new leaves. These trees are called deciduous trees. Oaks, maples, willows, and many other types of trees are deciduous.

In places that have cold winters and warm summers, most deciduous trees lose their leaves in autumn. Leaves need water to stay alive and to make food. A tree gets water from the soil. But in winter, the water in the soil turns to ice. The roots can’t take in this frozen water. There is no water for the trees.

In late summer, the tree begins to prepare for winter. A thick layer grows where each leaf’s stem is attached to the twig. Water can no longer get into the leaves. The leaves dry up, fall to the ground, and die.

In springtime, the ground warms up. The ice melts. The soil is wet again. Then a tree’s roots start taking in water, and the tree grows new leaves.

But not all broadleaf trees are deciduous. In warmer parts of the world, broadleaf trees stay green all year. They are called broadleaf evergreens. They lose just a few leaves at a time. The eucalyptus, or gum, trees of Australia are broadleaf evergreens.

Picture Credit : Google

Can you climb a maize plant or a tulip? Can you swing from a daisy? Of course not! But a tree is a different matter entirely.

Trees are tall, sturdy plants with woody stems called trunks. Branches grow from the trunk, usually quite far off the ground. It’s the trunk that makes a tree so strong. The trunk supports the tree.

The trunk also has several layers, each with an important job to do. Tree trunks are covered with a tough outer skin. Most trees have a hard, dry skin called bark. The bark protects the soft inside part of the tree. The next layer carries food made by the leaves to other parts of the tree. Next to this layer is the part of the trunk that makes the bark and new wood. Further inside is the wood. Some wood carries water around the tree. The inner wood helps support the tree.

In regions where trees make a new layer of wood once a year, the layers form a series of rings. After the tree has been cut down, each year’s layer of wood can be seen as a ring. A tree with 50 rings has lived for 50 years. The rings also reveal the tree’s life story. Narrow rings show that there was not much water or sunlight that year. Wider rings mean more water and sunlight were available, and more growth occurred.

Not all plants have to make seeds to grow new plants. Some plants can make copies of themselves without the help of another plant.

The good-luck plant grows new plants around the edges of its leaves.

If you plant a potato, a new plant will sprout from it! A potato is a tuber. New stems sprout from a tuber’s bud, called an eye.

The leaves and stems of some new plants grow out of underground buds called bulbs. Flowers such as lilies, tulips, and crocuses grow from bulbs. Onion and garlic plants have bulbs you can eat!

Some plants grow copies of themselves by sending off shoots. Mint and some kinds of grasses have underground stems from which new plants will grow. Strawberry plants produce stems called runners that grow sideways. New plants grow on the runners and root themselves wherever they touch the ground.

Picture Credit : Google

Like all living things, plants start their lives, grow, reproduce, and die. These steps make up a plant’s life cycle.

A seed plant begins when a seed germinates, or sprouts. A tiny root bursts out of the seed’s shell and pushes down into the ground in search of water. A tiny stem pushes up through the soil in search of sunlight. A new plant soon pokes its head above the ground.

The plant grows. Its roots take in water. Its leaves make food. After a time, the plant is fully grown. Small plants may become fully grown in a few weeks or months. A huge tree may take hundreds of years or more.

When a plant is ready to reproduce, it makes flowers or cones. The flowers and cones make pollen and eggs. The pollen and eggs join. Then new seeds form. Some seeds will be eaten by animals. Others will land in a place where they cannot grow. But some seeds will find a spot where the soil, water, and temperature are just right. These seeds will germinate, and the life cycle will begin again.

When a plant grows old, it dies. Its roots, stem, and leaves become part of the soil.

Picture Credit : Google

All seed plants have special seed-making parts. Most seed plants make their seeds inside flowers. The seed-making parts of a flower include long stalks. Some stalks have enlarged tips called anthers. Anthers make a golden dust called pollen. Other stalks have a sticky top called a stigma.

A seed starts to form when pollen from one flower falls onto the stigma of another flower of the same kind. The pollen travels down the stalk until it reaches a tiny egg. The pollen joins with the egg, which then grows into a seed.

Other seed plants make their seeds inside cones. There are two kinds of cones. One is small and delicate. It makes pollen. The other kind of cone is covered with wood scales and makes eggs. A seed starts to form when pollen blows from the delicate cones and lands on the scaly cones. The pollen and the eggs join. The scales close around the developing seeds. When the seeds are ripe, the scales open up again, and the seeds fall from the cones.

Picture Credit : Google

Plants can’t move around. So how do you think they spread their pollen to make seeds? Most plants use the wind or animals to help them pollinate.

All grasses and many trees, such as hazels and birches, scatter their pollen on the wind. The anthers of these plants hang out of the flower so that a puff of wind can carry away the pollen. The stigmas of these plants also hang out of the flower. They can catch the pollen as it blows past.

Insects, birds, and bats help spread the pollen of some plants. The flowers of these plants attract the animals. Many such flowers are full of sweet-tasting juice called nectar that bees and other animals like to eat. Some flowers “advertise” their supply of nectar with strong scents and bright colours.

When an animal visits a flower to sip the nectar, pollen brushes off onto its body. Then, when it visits the next flower, the pollen on its body brushes off into that flower.

Picture Credit : Google

A seed is a baby plant and a bundle of food all wrapped up in a package.

Different kinds of plants have different kinds of seeds. Some seeds are as big as a tennis ball. Others are smaller than a grain of sand. Some are round, some are flat, and some are long and thin. But in every kind of seed a baby plant, with its store of food, is waiting to grow.

In places that have cold winters, springtime is come-to-life time for seeds. Water from melting snow and spring rains sinks into the ground and soaks into the seed. The seed’s tough shell – the cover of the package – becomes soft. The food inside the shell swells up with water. Then the shell bursts open.

The baby plant pushes out. It uses its store of food to begin growing. A tiny root pushes down into the ground in search of water. A tiny stem grows up through the soil in search of sunlight.

As the plant grows, it uses its store of food. When it pokes its head above the ground into the sunshine, the plant begins to make its own food. It makes food out of sunlight, air, and water that its roots find.

Picture Credit : Google

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.