Getting to Know Plants PDF

7 Getting to Know Plants G o outside and observe all the plants of different kinds. Can you label plants around you. Do you see the stem, branches, roots, leaves, and that some plants are small, flowers of the plant shown in Fig.7.1?...

7 Getting to Know Plants G o outside and observe all the plants of different kinds. Can you label plants around you. Do you see the stem, branches, roots, leaves, and that some plants are small, flowers of the plant shown in Fig.7.1? d some very big, while some are just Colour the parts of the plant. e patches of green on the soil? h Some have green leaves, while some others have T i s reddish ones. Some have l huge red flowers, some have R b tiny blue ones, while some E have none. We do see a u variety of plants existing all C p around us — near our homes, in the school N e ground, on the way to the © er school, in the parks and gardens, isn’t it? Fig. 7.2 A Nature walk! Let us get to know the different b parts of any plant. This will help us Let us now go on a Nature walk, understand the differences between make friends with many different o kinds of plants and examine them t closely (Fig. 7.2). t 7.1 HERBS, SHRUBS AND TREES o Activity 1 n Look closely at the stem and branches of: 1. Plants much smaller than you. 2. Plants that are about your size, and 3. Plants which are much taller than you. Feel their stem and try to bend them Fig. 7.1 Parts of a plant gently to see if they are tender or hard. 52 SCIENCE  Table 7.1 Categories of plants Column 3 Plant Column 1 Column 2 Column name Height Where do the branches 4 Stem appear Higher up Green Tender Thick Hard At the base on the Category of the stem stem of plant Shorter Tomato than me Yes Yes Herb d Much e Mango taller Yes Yes Yes T ree than me h Slightly T s Lemon taller Yes Yes Shrub i than me R b l C E u p Take care that the stem does not break. 2 and 3 for many more plants. Fill N e Hug the tall plants to see how thick their Column 4 after you have studied later © er stems are! part of this section. We also need to notice from where the Based on these characters most branches grow in some plants — close to plants can be classified into three b the ground or higher up on the stem. categories: herbs, shrubs and trees. An We will now group all the plants we example of each is shown in Fig.7.3. o observed, in Table 7.1. Some examples t are shown. You can fill the Columns 1, t Suggestion: Work in groups of 4-5 students in doing activities suggested o in this Chapter so that a minimum n number of plants are uprooted. Use weeds with soft stems for the (a) activities. Do you know what weeds are? In crop fields, lawns, or in pots, often some unwanted plants or weeds start growing. Have you seen farmers removing these weeds from (b) (c) their fields? Fig.7.3 (a) Herb, (b) shrub and (c) tree GETTING TO KNOW PLANTS 53  Plants with green and tender stems are different from the herbs, shrubs are called herbs. They are usually short and trees. and may not have many branches Perhaps there are some plants in [Fig.7.3 (a)]. your school or at home that you take Some plants have the stem care of. Write down the names of any branching out near the base. The stem two trees, shrubs, herbs or creepers is hard but not very thick. Such plants growing in your house or school. are called shrubs [Fig.7.3(b)]. 7.2 STEM d Some plants are very tall and have e hard and thick brown stem. The stems Activity 2 have branches in the upper part, much h We would require a glass, water, red ink, above the ground. Such plants are a herb, and a blade for this activity. T s called trees [Fig.7.3(c)]. i Pour water to fill one-third of the l Based on the above characteristics glass. Add a few drops of red ink to the R can you now correctly classify the plants b water. Cut the base of the stem of the listed by you and complete column 4 in E u Table 7.1? C e p Paheli wonders what kind of stem — the N money plant, beanstalk, gourd plants and © er grape vines have. Do observe some of these plants. How are these different from a herb, a shrub or a tree? Why do you think b some of them need support to climb upwards? Fig. 7.5 What does the stem do? o herb and put it in the glass as shown in t Fig.7.5. Observe it the next day. t Do any of the parts of the herb appear o to have red colour? If yes, how do you Plants with weak think the colour reached there? n stems that cannot stand You can cut the stem across and upright and spread on look for the red colour inside the stem the ground are called ( Fig. 7.6). creepers, while those From this activity we see that water that take support on moves up the stem. In other words, stem neighbouring structures conducts water. Just like the red ink, and climb up are called Fig. 7.4 minerals dissolved in water also move climbers ( Fig.7.4 ). These Climbers up in the stem, along with the water. 54 SCIENCE  7.3 LEAF Look at leaves of plants around you and draw them in your notebook. Are all the leaves the same in size, shape and colour? How are they attached to the stem? (a) (b) The part of a leaf by which it is attached Fig. 7.6 (a) Cutting the stem, (b) its enlarged view to the stem is called petiole. The broad, d The water and minerals go to leaves and green part of the leaf is called lamina e other plant parts attached to the stem, (Fig. 7.8). Can you identify these parts of the leaves in plants around you? Do h through narrow tubes inside the stem. Paheli did this activity with herbs all the leaves have petioles? T i s having white flowers. She put one l Lamina Petiole branch with a white flower in the water R b in glass A and added a few drops of red E ink to the water. She did a funny thing u with another branch. She split it half C p way along its length and put the two Fig. 7.8 A leaf ends in the water in glasses B and C N e Let us get to know the leaf better by (Fig. 7.7). She put a few drops of red © er taking its impression! If you thought that leaves cannot sign, here is an activity which will make you think again. b Activity 3 Put a leaf under a white sheet of paper o or a sheet in your notebook. Hold it in t place as shown in Fig. 7.9. Hold your t Fig. 7.7 Paheli’s flowers pencil tip sideways and rub it on the o ink in glass B and blue ink in glass C. portion of the paper having the leaf below She wants you to guess what would it. Did you get an n happen to the flower in glass A and the impression with flower put jointly in B and C. some lines in it? When you had cut across the stem Are they similar to in Activity 2, did you notice a number those on the leaf? of spots of red colour arranged in a ring These lines on inside the stem? Does this explain the the leaf are called results that Paheli obtained? Try this veins. Do you see Fig. 7.9 Taking an activity yourself! a thick vein in the impression of a leaf GETTING TO KNOW PLANTS 55 Midrib Veins (a) (b) d Fig. 7.10 Leaf venation (a) reticulate and (b) parallel Fig. 7.11 What does the leaf do? e middle of the leaf? This vein is called the Are there any droplets of water in any h midrib. The design made by veins in a of the bags? Which bag has the droplets? s leaf is called the leaf venation. If this How do you think they got there? [Don’t T l i design is net-like on both sides of forget to remove the polythene bag after R midrib, the venation is reticulate the activity!] b [Fig. 7.10 (a)]. In the leaves of grass you Water comes out of leaves in the form E u might have seen that the veins are parallel of vapour by a process called C to one another. This is parallel venation transpiration. Plants release a lot of water p [(Fig. 7.10 (b)]. Observe the venation in into the air through this process. We will N e as many leaves as you can without learn more about this in Chapter 14. © er removing them from the plant. Draw the Why did we tie a bag around the pattern and write names of some plants leaves? Would we have seen the water having reticulate and parallel venation. from the transpiration of plants b Shall we now find out some of the otherwise? What makes the water functions of a leaf? appear on the polythene bag? In o Chapter 5, we noticed water changing Activity 4 t into different forms in some of our We will require a herb, two transparent activities. Can you think of these and t polythene bags and some string. name the process that makes water o Do this activity during day time on a drops appear on the polythene bag? sunny day. Use a healthy, well watered Leaves also have another function. n plant that has been growing in the sun, Let us study this. for this activity. Enclose a leafy branch of the plant in a polythene bag and tie Activity 5 up its mouth as shown in Fig. 7.11. Tie We would require a leaf, spirit, a beaker, up the mouth of the empty polythene test tube, burner, water, a plate and bag and keep it also in the sun. iodine solution for this activity. After a few hours, observe the inner Put a leaf in a test tube and pour surface of the bags. What do you see? spirit to completely cover the leaf. Now, 56 SCIENCE  ultimately gets stored in different parts of plant as starch. How do we know that the leaf has prepared the starch and not received it from another part of the plant? To test this, the above activity can be repeated with a little difference. Place a potted plant with green d leaves, in a dark room for a day or two. e Fig. 7.12 What does the leaf contain? Now, cover a portion of a leaf of the plant completely with black paper and leave h put the test tube in a beaker half filled the plant in the Sun for a day. Remove with water. Heat the beaker till all the T s the leaf covered in black paper and i green colour from the leaf comes out l repeat the test for starch. into the spirit in the test tube. Take out R What do you see? Which part of the b the leaf carefully and wash it in water. leaf shows the presence of starch? Does E Put it on a plate and pour some iodine u this help us understand that leaves solution over it (Fig. 7.12). C produce starch in the presence p Note: Since the activity involves the of sunlight? N e use of spirit and heating, it is advised We see that the stem supplies leaf © er that it is demonstrated by the teacher with water. The leaf uses the water to in the class. make food. The leaves also lose water through transpiration.How do the stem What do you observe? Compare your b and leaves get the water? That is where observations with those done in the roots come in! Chapter 2, when you tested food for o presence of different nutrients. Does this 7.4 ROOT t mean that the leaf has starch in it? Look at Fig. 7.13. Who do you think is t In Chapter 2, we saw that a slice of watering their plant correctly, Paheli or Boojho? Why? o raw potato also shows the presence of starch. Potatoes get this starch from n other parts of the plant and store it. However, leaves prepared their food in the presence of sunlight and a green coloured substance present in them. For this, they use water and carbon dioxide from air. This process is called photosynthesis. Oxygen is given out in this process. The food prepared by leaves Fig. 7.13 Watering the plants GETTING TO KNOW PLANTS 57  Which part of the plant is in the soil? Activity 7 Let us learn more about this part from We would require seeds of gram and the following activities. maize, cotton wool, katori and some Activity 6 water. You would require two pots, some soil, Take two katoris. Place some wet khurpi (for digging), blade or a pair of cotton wool in them. Put 3 or 4 seeds scissors and water. This activity is to be of gram in one and maize in the other. Keep the cotton wet by sprinkling d done in groups of 4-5 students. Select two weeds of the same kind water every day, until the sprouts have e from an open ground and dig them out. grown into young plants. After a week h Take care that their roots do not break. try to separate the young plants from the cotton wool (Fig. 7.15). s Plant one of the weeds in the soil in pot T i A [Fig. 7.14 (a)]. Cut off the roots from R l the other weed and plant it in the soil b in pot B [Fig. 7.14 (b)]. Water them E regularly. Observe the plants after a u week. Are both plants healthy? N C e p © er Fig. 7.15 Young plants grown on cotton wool Was it easy to separate the cotton wool b from the roots? Why? In Activity 6, we could not easily pull o out the plants from the soil, right? We t dug them out. The roots help in holding the plant firmly in the soil. They are said t (a) (b) to anchor the plant to the soil. o You have seen that there are different Fig. 7.14 (a) Weed with roots, and kinds of stems and leaves. Do the roots n (b) without roots also show a variety? Let us find out. Both the plants are watered regularly, but, one is without roots, isn’t Activity 8 it? Does this activity help you Study Fig. 7.16 (a) and (b) carefully. understand an important function of the Now, look at the roots of the gram plants root? you have pulled out from the cotton Let us do an activity to study another wool. Do they look like the roots shown function of root. in Fig. 7.16 (a) or those in Fig. 7.16 (b)? 58 SCIENCE  For roots of the kind shown in Fig.7.17 (a), the main root is called tap root and the smaller roots are called lateral roots. Plants with roots as shown in Fig. 7.17 (b) do not have any main (a) root. All roots seem similar and these (b) are called fibrous roots. Fig 7.16 (a) Roots of_______________ Separate the weeds you have collected d (b) Roots of_______________ into (a) those that have tap roots and e How about the roots of the maize plant? (b) those that have fibrous roots. Look Write ‘gram’ or ‘maize’ in the blank at the leaves of the plants in Group (a). h spaces in the figure after matching the What kind of venation do they have? T s roots with the figures. What kind of venation do you see for l i In what way are the roots of gram plants of Group (b)? R and maize similar? In what way are they Do you notice that leaf venation and b different? There seem to be two different the type of roots in a plant are related E u types of roots, isn’t it? Are there also in a very interesting way? In Table 7.2, C other types of roots? Let us find out. can you match the type of leaf venation p and the type of roots for some plants Activity 9 N e you have studied in all the activities © er Go to an open ground where many so far? weeds are growing. Dig out a few weeds, wash the soil off the roots and observe Boojho has a brilliant idea! If he b them. Do you find that all the weeds wants to know what kind of roots a that you have dug out have either the plant has, he need not pull it out. kind of roots shown in Fig. 7.17 (a) or o He just has to look at its leaves! t as in Fig. 7.17 (b)? o t Table 7.2 Types of roots and types of leaf venation n Name of Type of leaf Type of plant venation roots We have learnt that roots absorb (a) (b) water and minerals from the soil and Fig. 7.17 (a) Taproot and (b) fibrous roots the stem conducts these to leaves and GETTING TO KNOW PLANTS 59 other parts of the plant. The leaves Which colour did you use for the prepare food. This food travels through flower in Fig. 7.1? Are all flowers the stem and is stored in different parts colourful? Have you ever seen flowers of a plant. We eat some of these as roots— on the plants of grass, wheat, maize, like carrot, radish, sweet potato, turnip mango or guava? If you see any flowers and tapioca. We also eat many other in these plants, are they brightly parts of a plant where the food is stored. coloured? Do you agree that stem is like a two Let us study a few flowers closely. d way street? Write down what goes up When choosing flowers to study, avoid e the stem and what comes down, using marigold, chrysanthemum or in Fig. 7.18. h sunflower. You will learn in higher classes that they are not single flowers, T i s but, groups of flowers. R b l Activity 10 E We would require one bud and two fresh u flowers each, of any of the following– C p datura, china rose, mustard, brinjal, e lady’s finger, gulmohur. Also a blade, a N Fig. 7.18. A stem as a two way street! © er glass slide or a sheet of paper, a In the next section, we will study magnifying glass and water. about the structure of a flower. Observe Fig. 7.20 carefully. Look at the prominent parts of the open flower. b 7.5 FLOWER These are the petals of the flower. You are shown three branches of a rose Different flowers have petals of different o in Fig 7.19 (a), (b) and (c). Which one colours. t will help you best to recognize the plant? Where do you think the petals are in a t closed bud? Which is the most prominent part in a bud? Did you see that this part o is made of small leaf-like structures? They n Petals (a) (b) (c) Sepals Fig 7.19 Rose: (a) A leafless branch (b) A branch with leaves (c) A branch with leaves and flowers Fig. 7.20 Bud and flower 60 SCIENCE  Table 7.3 Observations on flowers Number Number Are the sepals Stamens are Pistil Name of and colour and colour joined together they free or Present/ flower of petals of sepals or separate? joined to petals? absent Rose Many 5 (Colour?) Separate Free Present (Colour?) d are called sepals. Take a flower and illustration and identify the stamens and observe its petals and sepals. Now, pistil in your flower. e answer the following questions: Look at Fig 7.23 carefully. It shows h How many sepals does it have? the different kinds of stamens present s Are they joined together? T i What are the colours of the petals R l and the sepals? b How many petals does your flower E have? u Are they joined to one another or are C p they separate? N e Do the flowers with joined sepals have Fig. 7.21 A bell shaped flower © er petals that are separate or are they joined together? Make a table based on the observations of the whole class b (Table 7.3). Add observations to this table, from a field trip to a locality where Stamens Pistil o there are plants with flowers. Fill the t last two columns after you have gone Fig. 7.22 Parts of a flower t through the entire section. o To see the inner parts of the flower clearly, you have to cut it open, if its n petals are joined. For example, in datura and other bell shape flowers, the petals have to be cut lengthwise and spread Anther out so that the inner parts can be seen clearly (Fig. 7.21). Filament Remove the sepals and petals to see the rest of the parts. Study the Fig. 7.22 carefully, compare your flower with the Fig. 7.23 Parts of a stamen GETTING TO KNOW PLANTS 61  in different flowers. Can Ovules Style Stigma you recognise both the parts of the stamens in your flower? How many stamens are there in Ovary your flower? Draw one stamen and label its parts. d The innermost part e Fig. 7.24 Parts of of a flower is called the a pistil pistil. If you cannot see h Fig. 7.26 Inner structure of an ovary it completely, remove the remaining (a) longitudinal cut, (b) transverse cut T s stamens. Identify the parts of the pistil i w a y s a s s h o w n i n F i g. 7. 2 5. To l with the help of Fig. 7.24. R Draw a neat, labelled diagram of the prevent them from drying, put a drop b pistil of your flower. of water on each of the two pieces of E the ovary, you have cut. u Activity 11 Observe the inner parts of the ovary C p Let us now study the structure of the using a lens (Fig. 7.26). Do you see some N e ovary of a flower (Fig. 7.24). It is the small bead like structures inside the © er lowermost and swollen part of the pistil. ovary? They are called ovules. Draw and We will cut this part to study how it looks label the inner parts of the ovary in your inside! Look at Fig. 7.25 (a) and (b) notebook. carefully to understand how to cut the On your field trip, try to find out the b ovary of a flower. names of as many of the flowers as you Take two ovaries from different can by asking the gardener or any other o person. Remember, not to pluck more t flowers. Cut them in two different flowers than you need. Based on what t you have filled in Table 7.3, answer the o following questions. Do all flowers have sepals, petals, n stamens and pistils? Are there flowers that do not have any of these? Are there flowers which have parts other than these? Did you find any flowers which have sepals and petals that look similar? (a) (b) Did you find any flowers in which Fig. 7.25 Cutting an ovary (a) longitudinal cut the number of sepals is different from and (b) transverse cut the number of petals? 62 SCIENCE  Do you now agree that the structure We have studied some features and of the flower is not always the same? functions of leaves, stems and roots. The number of sepals, petals, stamens We studied the structure of different and pistils may also be different in flowers. We will learn about the function different flowers. Sometimes, some of of flowers in higher classes. We will also these parts may even be absent! learn about fruits in higher classes. Climbers Petiole e d h Conduct Photosynthesis T i s Creepers Pistil R l Fibrous roots Reticulate venation Herbs E u b Sepal C Lamina Shrubs Lateral roots N e p Stamen © er Midrib Taproot Ovule T ranspiration b Parallel Venation T rees o Petal Veins t t o „ Plants are usually grouped into herbs, shrubs, trees, and climbers based on their height, stems and branches. n „ The stem bears leaves, flowers and fruits. „ A leaf usually has a petiole and a lamina. „ The pattern of veins on the leaf is called venation. It can be reticulate or parallel. „ Leaves give out water vapour through the process of transpiration. „ Green leaves make their food by the process of photosynthesis using carbon dioxide and water in the presence of sunlight. GETTING TO KNOW PLANTS 63  „ Roots absorb water and minerals from the soil and anchor the plant firmly in the soil. „ Roots are mainly of two types: tap root and fibrous roots. „ Plants having leaves with reticulate venation have tap roots while plants having leaves with parallel venation have fibrous roots. „ The stem conducts water from roots to the leaves (and other parts) and food from leaves to other parts of the plant. „ The parts of a flower are sepals, petals, stamens and pistil. e d h 1. Correct the following statements and rewrite them in your notebook. s (a) Stem absorbs water and minerals from the soil. T i (b) Leaves hold the plant upright. R l (c) Roots conduct water to the leaves. b (d) The number of petals and sepals in a flower is always equal. E u (e) If the sepals of a flower are joined together, its petals are also joined C together. p (f) If the petals of a flower are joined together, then the pistil is joined to the N e petal. © er 2. Draw (a) a leaf, (b) a taproot and (c) a flower, you have studied for Table 7.3. 3. Can you find a plant in your house or in your neighborhood, which has a long but a weak stem? Write its name. In which category would you classify it? b 4. What is the function of a stem in a plant? 5. Which of the following leaves have reticulate venation? o Wheat, tulsi, maize, grass, coriander (dhania), China rose t 6. If a plant has fibrous root, what type of venation do its leaves likely to have? t 7. If a plant has leaves with reticulate venation, what kind of roots will it have? o 8. Is it possible for you to recognize the leaves without seeing them? How? n 9. Write the names of the parts of a flower. 10. Which of the following plants have you seen? of those that you have seen, which one have flowers? Grass, maize, wheat, chilli, tomato, tulsi, pipal, shisham, banyan, mango, jamun, guava, pomegranate, papaya, banana, lemon, sugarcane, potato, groundnut 11. Name the part of the plant which produces its food. Name this process. 12. In which part of a flower, you are likely to find the ovary? 13. Name two flowers, each with joined and separated sepals. 64 SCIENCE  SUGGESTED PROJECT AND ACTIVITIES 1. BECOME A LEAF EXPERT Do this activity with a number of leaves over a period of a few weeks. For every leaf that you wish to study, pluck it and wrap it in a wet cloth and take it home. Now, put your leaf in a newspaper and place a heavy book on it. You can also put it under your mattress or a trunk! Take out the leaf after a week. Paste it on a paper and write a poem or story about it. With your leaf collection pasted in a book (a Herbarium), you can become quite an expert about leaves! d 2. Names of plant parts are hidden in this grid. Search for them by going up, e down, or even diagonally forward as well as backward. Have fun! h O V U L E L Y T S T E M T s V E I N W Q H E R B P I l i A N I M A L Z E X R N D R b R F I L A M E N T M U R E u Y A R A B L C O D B E I C L E E U O F O L G H I B e p A L H I I R J A L K U R N © er T M T N O T P P Q R R A E E N S T U F E H V W N P Y A M G I T S Z Z N C b F L O W E R E H T N A H o S T A M E N N S E P A L t t no GETTING TO KNOW PLANTS 65