Most plants have similar external features such as leaves, stems and flowers. Certainexternal features of these parts can be similar or different. Plants can be grouped according to the external features. Plants which are similar in a certain external feature can be put in the same group. Plants can be also be grouped according to their similarities in other external features such as thorns and leaves.
SCIENCE YEAR 3 (PLANTS)
UMATHEVI A/P BALAKRISHNAN --- NO.MATRIK : D20102040576
Sunday, 4 December 2011
SUMMARY
Most plants have similar external features such as leaves, stems and flowers. Certainexternal features of these parts can be similar or different. Plants can be grouped according to the external features. Plants which are similar in a certain external feature can be put in the same group. Plants can be also be grouped according to their similarities in other external features such as thorns and leaves.
Part of Sunflower
Sunflowers – Planting to Harvest
Planting
The seed is about half an inch long. It has a hard, striped covering. The covering
protects the soft inside (the part that is tasty to eat). What the covering protects,
and what you like to eat, is the food that the sunflower needs to begin to grow
into a plant. Let’s plant the seed and watch it change and grow!
In the spring, when the ground is warm, and the soil is soft, you can plant your
seed. The seed needs to be buried in the soil where it can be warmed by the
sun, watered by the rain, and fed by nutrients and oxygen trapped in the soil.
Now underground, the hard covering of your seed splits open, and a little, white
root appears! The root is the first part of the sunflower to grow. It will grow
downward because of the force of gravity. The roots will hold the sunflower in the
ground. This is a big job because your sunflower may grow to be over seven feet
tall! The roots will also help feed the plant so that it can grow to be so tall.
Growing
I see it! Your sunflower has begun to grow! There is a small green shoot pushing
up out of the soil. This is the beginning of the plant’s stem, and it grows up into
the air (instead of down into the ground like the root) because it needs the sun’s
light in order to do its job.
Leaves start to form in pairs on the stem as it grows taller. The leaves and the
roots of your sunflower both feed it so it can become big and strong and then
flower. The roots collect water and nutrients from the soil. The leaves catch
energy from the sun. The energy helps the plant create food in a process called
photosynthesis. This is a big word! It is bigger than I, Araña Pequeña!
Because the leaves cannot produce food without energy from the sun, your
sunflower leans towards the sunlight all day. As the sun moves from east to west
across the sky, the plant will lean directly toward it.
Now that the leaves are helping the roots feed your plant, it grows very fast. In
two months, your sunflower may grow to be seven feet tall! How much do you
grow in two months? In a year?
Flowering
Look! There is a bud forming at the top of the stem, above the highest pair of
leaves. The bud is the protected, growing flower. There are strong, green,
pointed petals covering it as it becomes bigger.
When the bud begins to form, your sunflower won’t grow much taller. The bud is
eating up the food that was used before to make leaves and a strong, tall stem.
One morning, your sunflower bud begins to open. The strong, green petals open
slowly. Watch the big yellow petals appear! These have been growing inside the
bud. Inside the circle of bright yellow petals is a dark disk. This disk is made up of
hundreds of tiny buds. These buds are smaller than I, Araña Pequeña! They
won’t grow very big, but they give your sunflower a special name. Your sunflower
is a composite flower – or a number of flowers that together form what looks
like only one, large flower. Let’s take a closer look at this composite flower!
Each tiny bud in the disk has its own reproductive parts. The female part is called
the pistil. The pistil is made up of a stigma, a style and an ovary. The male part
is called the stamen. The stamen is made up of a filament and an anther.
Do you know how a sunflower reproduces? The process is called pollination.
And sunflowers need insects to help them. Watch the bee that has landed on
your sunflower! The bee is attracted by the bright yellow petals. When the bee
lands on the sunflower, pollen from the stamen (the male part) of the flower gets
stuck to the legs of the bee. When the bee flies away and lands on a different
sunflower some of the pollen rubs off onto the pistil (the female part) of that
flower. This is how plants are pollinated.
Once one of the little flowers in the disk is pollinated, it can grow a seed.
Harvesting
More and more seeds start to grow in the sunflower disk. The food from the
roots and from photosynthesis is now going into the growing seeds. Your
sunflower may have more than 2000 seeds!
By fall, all the seeds have grown to their full size, about half an inch long. Now
farmers will harvest the seeds. Some of the seeds will be eaten by people like
you and me. The ones that are not harvest might be eaten by small animals like
squirrels and chipmunks. Do you know what else sunflower seeds are used for?
Sunflower seeds can be pressed to make oil. The oil is used for cooking or in
paint or soap. They are also used as birdseed, and to feed farm animals. And
some of the seeds are saved to be planted. Without these seeds, we wouldn’t get
any new sunflower plants next spring!
External Features of Plants
Most plants have the same main part : leaves, stems, flowers and fruits. However these features do not look the same.
Most plants have green leaves. However, some have yellow or red leaves. Some leaves are shiny and some are dull. The surface of leaves are smooth or rough. The shape of leaves can be irregular, oval, round or long.
OBJECTIVE
You will learn :
- to observe and recognise external features of plants.
- that plants can be grouped according to external features.
- that plants can be grouped in many ways
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