How Plants Grow

All plants need water to live. They do not take in food as animals do, but make their own using water from the ground, and carbon dioxide gas from the air. Water is absorbed through a plant's roots. It travels up through the stem or trunk into the leaves, shoots, and flowers. The water also carries the nutrients from the soil to all parts of the plant. In the leaves, nutrients and water are used for photosynthesis, the process of making energy from light. Excess water not needed by the plant evaporates back into air in the form of water vapor in a process called transpiration. You can see how much water vapor is transpired by a plant in the first experiment.

EVAPORATION IN ACTION

You will need :
1) House plant
2) Watering can
3) Clear plastic bag
4) Tape
5) Scissors

Step 1
Water the house plant well using a watering can. Water the plant at the base, so the roots can draw the water up. If you water the plant from the top, water just the soil, not the plant itself.

Step 2
Place a large, transparent plastic bag over the plant, taking care not to damage the leaves. Tape the bag tightly around the pot. Leave the plant overnight.

Step 3
Look at the plant the next day. Inside the bag, water vapor given off by the plant turns back into water. The air inside is warm and moist, like the air in a rainforest.

When a seed begins to grow, we say that it is has germinated. Germination occurs when conditions are warm and moist enough for the seed to swell and split its skin. A tiny root grows downward, and a thin shoot pushes upward toward the light. The second project shows you how to germinate a seed and help it grow into a tree. Germinating a seed this way takes about two months.

GERMINATE AN ACORN

You will need :
1) 4in (diameter) flower pot
2) Soil mix
3) Gloves
4) Acorns or another tree's seeds
5) Trowel
6) Watering can

Step 1
Fill the flower pot with soil mix and bury an acorn just beneath the surface. Put it in a warm place and keep the soil moist. Plant several acorns, since one may not germinate.

Step 2
When a tiny tree starts to grow by itself, it is called a seedling. It needs light and and regular watering to grow well. Do not soak the soil with water, or the roots will rot and die.

Step 3
Your seedling should grow rapidly for a few weeks and then stop. During the winter, it will need little water. In the spring, you can take the seedling out of its pot and plant it outside.

MORE INFORMATION ON TREES

CONVERTING ENERGY :

Photosynthesis is the process through which plants use the water in the ground and the energy in sunlight to make their food. Leaves take in carbon dioxide and water to make oxygen and glucose (sugar). Glucose flows to all parts of the plant, supplying energy for growth. Oxygen gas escapes through the holes on the underside of the leaves. The oxygen is released back into the air. We need oxygen to breathe.

SURVIVAL IN THE WETLANDS :
Swamps are places where the ground is permanently waterlogged, such as in muddy river estuaries. Most trees cannot survive in swamps, because they need fresh water and air around their roots. Some types of mangroves have breathing roots that grow upward, so that their tips are above the surface of the water. Mangrove swamps are home to kingfishers, giant water bugs, crabs, turtles, crocodiles, and mudskippers, a type of fish that spends much of its time out of water.

FLOATING WATER : Trees pass millions of gallons of water vapor into the water each day. The vapor forms thick clouds of tiny water droplets over the forest.