5th Class Science Plants Plants

LEARNING OBJECTIVE

This lesson will help you to:

• Learn how plants grow from seeds.
• Learn about different methods of growing new plants.
• Understand the method of seed dispersal.
• Study various types of vegetation found on earth.

Amazing Facts

• A sunflower looks like one large flower, but each head is composed of hundreds of tiny flowers called floret, which ripen to become the seeds. This is the case for all plants in the sunflower family, including daisies, yarrow, goldenrod, asters, coreopsis, and bachelor’s buttons.
• The average strawberry has 200 seeds. It’s the only fruit that bears its seeds on the outside.
• Trees are the longest-living organisms on earth.
• The title for the world’s hottest chili pepper remains contested, Bhut Jolokia ‘, 401.5 times hotter than bottled hot pepper sauce, earned the Guinness world Records title in 2007, but severa hotter chillies claimed the title in 2011.

QUICK CONCEPT REVIEW

We already know about plants and their main parts. We Kg also know that plants prepare their own food and give Bus oxygen to breathe. We get food from plants. In this chapter, we shall learn about how a plant comes out of a seed and then becomes a tree.

How does a plant grow from the seed?

We know that plants grow from seeds and there are a lot of internal changes that take place in the seed when it grows into a new plant. Seeds need water, appropriate p temperature and a good quality soil to germinate. Till the time the new plantlet (seedling) grows its first leaves, it depends upon the food stored in the seed to grow. When the seedling develops its own leaves, it starts to become independent. The roots of the seedling start to extend downwards and the stem and leaves upwards. The roots g absorb water and nutrients from the soil and the leaves g absorb sunlight.

The stage of germination of seed ends here but the plant has just started to grow.

However, not only the seeds can form new plants, some other parts of plants such as roots, leaves and stems are also used to grow new plants out of them.

For example, the sweet potatoes can be grown from an old plant's roots. However, it is to be checked first whether the roots are still alive or not.

The stems of sugarcane and roses are used to grow new plants. The cutting of stem is planted into the soil and after some time a new plant grows out of it. This method is coiled CUTTING.                                 

And sometimes the stem is not separated from the tree. A branch of the tree while still attached to the tree, is buried into the earth and a new plant starts to grow from it after some time. It starts developing roots. Then it is

Detached from the parent plant. This method of using the stem to produce new plants is called LAYERING.

For example: Jasmine.

Sometimes, leaves of plants are also used to produce new plants such as in Bryophyllum.

But the most common method to grow plants remains through seeds.

DISPERSAL OF SEEDS

When the field is ploughed, the farmer disperses the seeds manually. But there are plants whose seeds are dispersed through insects or air.          

Dispersal of seeds means spreading the seeds so that they can grow.                                      

Air, water, small insects and animals help to disperse the seeds. Sometimes the seeds are dispersed with the effect of gravity. The heavy fruits such as apples and coconuts fall down on earth after ripening and this cause’s seed dispersal.                                      

Water also helps in seed dispersal. Seeds can actually travel a long distance with the help of water, the dispersal of water lily seed happens through water.

The flower of water lily produces a fruit which falls down to the bottom of pond after floating for some time on water.

The seed dispersal in palm trees also takes place through water.

You must have seen some feathery things flying around you sometimes. These are the seeds of dandelion which are dispersed through wind. The wind either makes the seeds float in air or it blows the seeds to fall on the ground.

Small insects and animals also help in dispersing the seeds. If an insect sits on a flower, its seeds get stuck to the legs of the insects and when the insect flies away it carries the seeds to some other place.

Real-Life Example

• In our daily cooking we use many types of seeds.
• Packed with anti-inflammatory fats, proteins and nutrients galore, nuts and seeds make a great addition to a healthy daily diet.

Historical preview

• The first potatoes were cultivated in Peru about 7,000 years ago.
• During the 1600s, tulips were so valuable in Holland that their bulbs were worth more than gold. The craze was called tulip mania, or tulipomania, and caused of the Dutch economy. Tulips can continue to grow as much as an inch per day after being cut.

Misconcept / Concept

Misconcept:  Peanuts are nuts.

Concept:  Peanuts are not nuts, but legumes related to beans and lentils. They have more protein, niacin, folate, and phytosterols than any nut, according to the National peanut Board.

Misconcept:  Garlic mustard is a type of garlic

Concept:  Garlic mustard is a member of the mustard family, not garlic. This invasive herb out competes native plants in the Eastern and Midwestern United States, posing a threat to

Other native plants and the species that depend on them.

When the animals eat something (a fruit) and go to the other places, sometimes they leave the seeds of the fruit at some place which helps in dispersal. In the same manner we also disperse the seeds when we eat out at a place, say any fruit on a picnic and we throw the left over somewhere.

IMPORTANCE OF FORESTS

There are plants and trees in a forest. But do you know that a forest is not only for trees and animals to live. There are people who live inside these forests and spend their lives there only. They are called tribal people. They are very much dependent upon the forests for their food and shelter. As they live inside the forests there are no grocery stores for them and hence they depend upon the fruits and vegetables that grow in the forests. They also do hunting and eat flesh.

They make their homes with mud, palm leaves and wood. But due to industrialization these forests are being cut and it is a danger for the tribal people. Also there is increase in number of buildings being constructed as the population is increasing. All these buildings are being constructed on forest lands. There are places in our cities where there used to be forests sometimes. As there is rapid increase in the deforestation, there is a danger to the tribal life and to our environment too. That's why the need to protect trees was felt. To protect trees and wildlife some parks and sanctuaries were made. Here the animals are fully protected from hunting and the trees also cannot be cut. It is a protected area within which the wildlife is protected.

Taking the importance of forests into consideration, the

K government makes these sanctuaries or parks to preserve these forests.

Some of the examples of National Parks are: Jim Corbett National Park, Kaziranga National park, etc. and the S sanctuaries are; Gir and Sukhna Lake.

National parks are the safe regions to make the wildlife better. Here any sort of foresting or agriculture is not allowed.

A sanctuary is a safe place in the forest where animals are protected. Here wood cutting and obtaining the forest products is prohibited.

IMPORTANCE OF PLANTS

Along with their contribution in our food and environment trees have religious values also. For example many trees such as tulsi plant, banana tree and peepal tree are      worshipped. Sandalwood is also used to worship. The leaves of a mango tree are also used in worships.

• A Tulsi plant (basil) is often found in homes as it has both medicinal and religious value.

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• We use different things obtained from plants, such as fruits and vegetables. But there are some things which we get from plants but do not use them in the same form. For example cotton is obtained from seeds of cotton plant and is used to make cotton clothes.

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• One more important thing which we get from plants is tea, which is made from tea leaves.    

A tea plant looks like as shown in the figure. The tea plants have thick leaves which are dark green in colour. It is quite different from what we use in our homes. The reason is that the tea leaves are processed before using them.

Tea plant is propagated from seeds or cuttings. This plant needs proper moisture and a particular type of soil to grow. It is cultivated on hillside. The plants on the higher places take more time to grow and develop better tastes. It needs hot and moist climate to grow. The tea plants prefer acidic soils. These are to be watered using soft water or rainfall only.

At times when there was no tea, people used to prefer to drink milk or buttermilk.

So in this chapter we have learnt that there are a lot of things associated with the plants and trees. They not only provide us with food but also shelter for tribes and wildlife animals.