Plant Diversity PDF

01 Plant Diversity 1.1 Morphological features of flowering plants Flowers and fruits naturally come to our mind when we state about trees. Do all varieties of trees produce flowers? Pay your attention to the ornamental plants in the garden given in Figure 1.1. Figure 1.1...

01 Plant Diversity 1.1 Morphological features of flowering plants Flowers and fruits naturally come to our mind when we state about trees. Do all varieties of trees produce flowers? Pay your attention to the ornamental plants in the garden given in Figure 1.1. Figure 1.1 view of a garden You can observe plants with flowers and without flowers. There are different varieties of plants in our environment. Engage in Activity 1.1 to find out whether all the trees bear flowers. Activity 1.1 Names and the pictures of several plants are given below. Although most of them are familiar to you, certain plants may not much familiar to you. Rose Fern ʻIddaʼ Gardenia ʻKoodaluʼ ʻOosi mallikaiʼ ʻKasiththumbaiʼ Science | Plant Diversity 1  Water Lily Turpentine 'Sal' Lotus Cycas Shoe flower Long bean (ʻOluʼ / ʻAlliʼ) 'Nagalingam' Curry leaves Drynaria ʻKataroluʼ Jasmine Cyperus Coconut Salvinia (Karapincha) (benduru) ʻKakkattanʼ Figure 1.2 Several different types of plants Prepare a table by grouping all the plants in Figure 1.2 into plants which bear flowers and plants which do not bear flowers. Compare your table with the following table. Table 1.1 Plants which bear flowers Plants which do not bear flowers Rose, ʻIddaʼ, Gardenia, Balsam, Cycas, Turpentine, Water lily, ʻSalʼ, Lotus, Shoe Salvinia, Cyperus, Drynaria, flower, Curry leaves, ʻkatarolu Z, Ferns Jasmine, Coconut, Long bean Now, it is clear to you that there are plants which produce flowers and that do not produce flowers in our environment. Plants which produce flowers are called flowering plants and plants which do not produce flowers are called non flowering plants. Assignment 1.1 ²² Observe plants in your home garden or in your school premises. ²² Identify them as flowering plants and non flowering plants. ²² Tabulate the plants you identified as flowering plants and non- flowering plants. 2 Science | Plant Diversity  1.2 Main parts of a flowering plant Observe the flowering plants in your surroundings. They are of different sizes. When you look at the trees you can observe small palnts as well as big trees among them. Their stems, roots, flowers and fruits are also different from each other. Therefore, plants show a great diversity in their size and morphological features, but all flowering plants have some common parts. Let's do Activity 1.2 to identify the main parts of a flowering plant. Assignment 1.2 Identification of main parts of a flowering plant ²² Select a small plant that produces flowers and fruits. e.g.:- ʻMonara Kudumbiya’, / ʻSeethaviyar Selugkalunerʼ ʻKuppameniyaʼ / ʻKuppaimaniʼ ²² Uproot it from the soil without breaking roots. ²² Remove soil around roots carefully ²² Press it between pages of newspapers. ²² Prepare a field book and paste the specimens in it after about one week. 7 Activity 1.2 The Figure 1.3 shows the parts of a 8 10 flowering plant. The main parts are 5 labelled from 1 to 11. 11 01. Tap root 08. Branches 02. Lateral roots 09. Fruits 9 6 03. Root system 10. Flowers 04. Stem 11. Shoot 4 05. Lateral buds (Axillary buds) 06. Leaves 1 07. Apical bud 3 2 Figure 1.3 Parts of a flowering plant Science | Plant Diversity 3  Identify the basic parts of a plant in Assignment 1.2 referring to Figure 1.3. Compare the pressed plant you have, with the pressed plants your friends have. Observe similarities as well as dissimilarities among the main parts of them. 1.3 Diversity of the parts of flowering plants The characteristic feature of the flowering plant is formation of flowers. Almost all parts such as stem, leaves, roots, buds, flowers and fruits can be seen in most of the plants. Plants show a great diversity among these parts. Diversity among roots Assignment 1.3 ²² Select a small grass plant and a ʻKuppameniyaʼ / ʻKuppaimaniʼ plant. ²² Uproot them carefully without damaging roots. ²² Wash the soil of the roots and press it. ²² Paste it on the field book after one week. Normally root system remains underground in the soil. There are two types of root systems. ²² Some plants have a single large root which originates from the base of the stem. It is called the tap root. Large number of roots are originated from the tap root. They are called lateral roots. This type of root system is called a tap root system. e.g.:- ʻKuppameniyaʼ/ ʻKuppaimaniʼ, Mango, Cashew ²² Some plants have a large number of small roots which are originated from base of the plant stem. This type of root system is called a fibrous root system. e.g.:- Coconut, Arecanut, Bamboo, Grass, ʻKitulʼ 4 Science | Plant Diversity  Tap root Fibrous roots Lateral root Figure 1.4 (a) Tap root system Figure 1.4 (b) Fibrous root system Activity 1.3 ²² Look at the root systems of two plants you pasted in your fieldbook ²² Observe the differences between root systems of those two plants. You will notice that 'kuppameniya', mango, cashew like plants have a tap root system whereas grass, coconut, arecanut, and bamboo trees have a fibrous root system. Functions of plant roots ²² Fix the plant to the soil ²² Absorb water and minerals dissolved in water (absorption) ²² Involve in vegetative propagation (vegetative reproduction) e.g.:- Curry leaves, ʻBeliʼ/ ʻVilvamʼ, Bread fruit In addition to these there are roots adapted for other functions. Let's do Assignment 1.4 to identify such roots. Assignment 1.4 ²² Uproot a mimosa plant without breaking its roots and wash the roots carefully ²² Draw the root system of it in a white drawing paper. ²² Paste it in the fieldbook. ²² Observe the yams of beetroot, carrot, sweet potato and manioc ²² Draw them on a white drawing paper and paste it in your fieldbook. Science | Plant Diversity 5  Manioc Beetroot Carrot Sweet potato Mimosa Figure 1.5 Different types of storage roots Small nodules like structures can be seen in the root system of Mimosa plant. Such nodules are known as root nodules. There are micro organisms called bacteria live inside them. These bacteria supply nitrogen nutrients required for the growth of Mimosa plant and root system supplies nutrients for the bacteria which live inside the nodules. Such nodules are present in plants such as ʻkathurumurungaʼ, beans and winged beans which belong to family Leguminosae. The other roots shown in Figure 1.5 are generally called as yams because food is stored in those roots. Food can be stored in tap root as well as lateral roots. Naturally roots grow downward into the soil, but you can observe some roots that grow above the soil. Figure 1.6 shows different types of roots that grow above the soil level. Aerial roots of orchid Prop roots of banyan Stilt roots of pandanus Climbing roots of betel Respiratory roots of ʻKiralaʼ/ ʻKinnaiʼ Figure 1.6 Roots adapted for various functions 6 Science | Plant Diversity  Activity 1.4 Arrange a field visit and identify the different types of roots shown in Figure 1.6. Study Table 1.2 and try to understand various functions of root types' Table 1.2 Different types of roots and their functions Type of root Example Functions Prop roots Banyan Support the branches Stilt roots Pandanus, ʻrampeʼ Support the stem Aerial roots Orchid Absorb water vapour from the atmosphere Some roots carryout photosynthesis Climbing roots Pepper Helps to climb the stem by attaching Betel to another stem R e s p i r a t o r y ʻKandolʼ/ʻKandalʼ Exchange of air with the atmosphere roots ʻKiralaʼ / ʻKinnaiʼ Storage roots Carrot Store food Beet Manioc Sweet potato Roots with Mimosa Bacteria live inside root nodules add root nodules Legumes (eg: nutrients to the soil. Thus make the Beans, Long beans, soil fertile. Winged beans) For extra knowledge Corks used as stoppers of bottles are taken from respiratory roots of ʻKiralaʼ/ʻKinnaiʼ plant. The porous or sponge nature of ʻKiralaʼ / ʻKinnaiʼ corks occur due to presence of very tiny pores and spaces in their roots. Science | Plant Diversity 7 Diversity among stems Recall the nature of plant stems that you have observed in your surrounding. You may have observed very strong stems, stems with thick bark as well as stems with various colours. There are plants that grow up with the help of supporters and run on the ground due to their weak stems. The basic difference in any type of the stem is that whether the stem divides into branches or not. Figure 1.7 A plant with unbranched stem Figure 1.8 A plant with branched stem e.g.:- Coconut, Arecanut, Kitul, e.g.:- Mango, Rambuttan, Cashew, Guava, Palmyrah, Paddy, Bamboo Shoe flower Functions of plant stem ²² It bears flowers, leaves, buds, fruits, seeds etc. ²² It supports the plant, by keeping rigid. ²² It transports water and food through plant body ²² Many plants produce new plants by stems. (vegetative reprodution) e.g.:- Shoe flower, Jasmine/ 'Saman pichcha' / 'Sadimalligai', Sweet potato, Manioc ²² Some plants have green colour stems to carryout photosynthesis e.g.:- ʻNawahandiʼ / ʻKallyʼ, ʻHeeressaʼ / ʻPirattaiʼ, Cotton, ʻHathawariyaʼ/ ʻSathavariʼ ²² Some aerial stems store food. e.g.:- Sugar cane, Kitul Eventhough most stems grow above the soil, some stems grow inside the soil. They are called underground stems. Underground stems, that grow inside soil, conduct (carryout) all the other functions, except 8 Science | Plant Diversity photosynthesis. Examples for underground stems are given in Figure 1.9 Ginger Potato Colocasia Leeks Onion Figure 1.9 Plants with underground stems Diversity among leaves Plant leaves also display a great diversity like other parts of the plant; based on shape, size and colour. Let's engage in Activity 1.5 to learn about diversity of leaves. Activity 1.5 yy Collect about ten different types of leaves from your home garden. yy e.g.:- Manioc, Curry leaves, Jak, Grass, Croton, ʻAkkapanaʼ / ʻSadaikaraichchanʼ , Pumpkin, ʻHathawariyaʼ/ ʻSathavariʼ, ʻKaturumurungaʼ/ ʻAgathiʼ. Study their similarities as well as dissimilarities, by observing them. Photosynthesis mainly occurs in a leaf of a plant. Plant leaves get energy from sunlight to do photosynthesis. Therefore leaves are arranged on the stem in a way to get maximum amount of sunlight. Eventhough leaves have different shapes, sizes and different colours, they all have Figure 1.10 Arrangement of plant leaves in plants to absorb common parts. Those common parts are maximum amount of sunlight shown in Figure 1.11. Science | Plant Diversity 9  Mid rib (Mid vein) Veinlets Pedicel/Stalk Leaf base Leaf tip Leaf margin Leaf blade Figure 1.11 Parts of a leaf Activity 1.6 Select a leaf of a plant you pressed and paste it on the fieldbook Identify all parts given in Figure 1.11 and label them. Leaf venation The arrangement of veinlets in the leaf is called leaf venation. There are two main venation patterns occur in plants. ² Reticulate venation ² Parallel venation Figure 1.12 A part of a plant leaf with reticulate Figure 1.13 A part of a plant leaf with venation parallel venation The branches initiated from the mid Veinlets parallel to the midrib rib spread as a net through out the spread in the leaf leaf eg:- Grass, Bamboo, Coconut, eg:- Shoe flower, Mango, Jak, Arecanut ‘Gotukola’/ ‘Vallarai’ You can observe leaf venation by observing lower surface of the plant leaf clearly. 10 Science | Plant Diversity  Assignment 1.5 Apply paint on the lower surfaces of some leaves and get copies of them to Shoe a white paper. Identify the type of leaf flower Mango ʻIddaʼ Jak venation and classify them as reticulate venation or parallel venation. Finally paste them in your fieldbook. Part of Part of Grass ʻKoboleelaʼ palmyrah Cocounut ʻThiruvaththiʼ leaf leaf Simple and compound leaves When the leaf blade of a leaf is not divided into segments it is called a simple leaf. e.g.:- Shoe flower, Jak, The leaf blade of some leaves are partially divided into segments. e.g.:- Manioc, Papaw Shoe flower Jak Papaw Figure 1.14 Several simple leaves Leaf blade of a compound leaf is completly divided into small leaf like parts called leaflets. These types of leaves with leaflets are called compound leaves. e.g.:- Coconut, Long beans, ʻKaturumurungaʼ/ ʻAgathiʼ, Tamarind, Curry Leaves Coconut Tamarind ‘Katurumurunga’/ ‘Agathi’ Figure 1.15 Several compound leaves Science | Plant Diversity 11 Functions of plant leaves ²² The most important function of a plant leaf is photosynthesis. Through photosynthesis plants produce food in leaves. ²² Some leaves are adapted to store water e.g.:- Aloe, ʻAkkapanaʼ / ʻSadaikaraichchanʼ Figure 1.16 Aloe Figure 1.17 ʻAkkapanaʼ/ Sadaikaraichchanʼ ²² Some leaves produce new plants. (vegetative reproduction) e.g.:- ʻAkkapanaʼ, Begonia Assignment 1.6 ²² Place a leaf of bryophyllum in between two blotting papers and keep it between the pages of a book for few days ²² Observe it after few days ²² Identify the roots arising from leaf margin. They are called adventitious roots ²² Cut the leaf into pieces and get new plants by planting those pieces Parts of a flower and thier diversity The main function of flowers is to produce fruits. The seeds inside the fruits produce new plants. These seeds are dispersed by various methods (by animals, wind, water, explosive mechanism) Flowers bear male and female reproductive structures. They combine and form seeds by sexual reproduction. Flower is the structure adapted for the sexual reproduction. 12 Science | Plant Diversity Structure of a flower The most attractive part of the plant is the flower. They differ greatly in size, smell, shape and colour. Assignment 1.7 ²² Collect different types of flowers ²² Draw their external appearance on a white paper ²² Write the name of the plant below the diagram. ²² Identify the parts of flowers and name them, by using Figures 1.18 and 1.19 Stigma Stigma Stamen Stamen Style Petal Petal Sepals Ovary Sepals Pedicel (flower stalk) Pedicel (stalk) Figure 1.18 External appearance of Figure 1.19 Longitudinal section of shoe flower shoe flower Flowers show great diversity among them, but they have a common structural plan. A typical flower consists of the following three parts. ² Sepals ² Petals ² Gynoecium/ Androecium All these parts can be easily observed in a shoe flower. Let's identify parts of a flower by observing longitudinal section of a shoe flower. (Figure 1.19) Science | Plant Diversity 13  Activity 1.7 ²² Select a bigger flower (e.g.:- Shoe flower, Thunbergia) ²² Cut and separate the flower into two parts longitudinally by carefully cutting it from the pedicel using a sharp blade ²² Use Figure 1.19 to show a diagram of the longitudinal section of a flower. Identify its parts and name them Sepals Sepals are generally green in colour. The main function of sepals is the protection of flower buds. Petals Petals are brightly coloured. They attract insects for pollination as well as protect the internal parts of the flower. Androecium anther Stamen of a flower is called androecium. Each stamen is made up of two parts filament yy anther Figure 1.20 A stamen of shoe flower yy filament The function of androecium is production of pollen. Different shapes of stamens can be seen in flowers Lotus ‘Sal’/ ‘Nagalingam’ ‘Niyagala’ / Sunflower ‘Karthikaipoo’ Figure 1.21 Different shapes of stamens in flowers 14 Science | Plant Diversity  Stigma Gynoecium Style Gynoecium contains following parts. ²² Stigma Ovary ²² Style Ovules ²² Ovary The function of gynoecium is the production of seeds. Figure 1.22 Gynoecium of a flower Activity 1.8 Using maximum number of examples complete Table 1.3 further with the help of the features of flowers that you have observed. one example is given for each section. Table 1.3 White coloured flowers ‘Idda’ / ‘Oosi mallikai’, Flowers with colourful petals Rose,........................ Flowers that bloom at night ‘Sepalika’ / ‘Pavala mallikai’ Flowers with sweet smell (fragrance) Jasmine/ ‘Samanpichcha’/‘Sadimalligai’ flowers with nectar ‘Kathurumurunga’ / ‘Agathi’ Diversity of fruits and seeds Fruits are formed from the flowers of flowering plants. Seeds are found inside the fruits. seeds produce new seedlings. Assignment 1.8 ²² Collect fruits and seeds that are fallen near trees in the school garden. (Collect the seeds into a seed box) ²² Collect fruits and seeds that are fallen under trees in your home garden. ²² Collect different types of fruits and seeds that are not found regularly. (Try to find the names of those plants) Science | Plant Diversity 15 Fruits and seeds are naturally adapted for dispersion. e.g.:- Cotton, ʻWaraʼ / ʻErukuʼ, ʻHoraʼ / ʻEnnaiʼ, ʻGammaluʼ / ʻThanakkuʼ Cotton ʻWaraʼ/ʻErukuʼ ʻHoraʼ/ʻEnnaiʼ ʻGammaluʼ/ ʻThanakkuʼ Figure1.23 Fruits and seeds which are dispersed by wind Assignment 1.9 Collect fruits and seeds as shown in Figure 1.23. List out the adaptations they show to be propagated by wind. Get assistance from your teacher. Arecanut Coconut ʻKottambaʼ, ʻDiya kaduruʼ Lotus ʻKottankachchiʼ ʻKulliththyʼ Figure 1.24 Fruits and seeds which are dispersed by water Assignment 1.10 Collect fruits and seeds as shown in Figure 1.24. List out the adaptations they show to be propagated by water. Get assistance from your teacher. Tomato Papaw Chillies Castor ʻNagadaranaʼ Figure 1.25 Fruits and seeds which are dispersed by animals ʻPulinagamʼ 16 Science | Plant Diversity  Assignment 1.11 ²² Collect fruits and seeds as shown in Figure 1.25. List out the adaptations they show to be propagated by animals. Get assistance from your teacher. 1.4 Monocotyledonous and dicotyledonous plants Flowering plants are mainly divided into two groups as monocotyledonous (monocots) and dicotyledonous (dicots). Do Assignment 1.13 to identify differences between two types of plants. Assingment 1.12 ²² Collect many seeds as far as possible from your kitchen e.g.:-Gram, Paddy/Rice, Green gram, Tamarind, Cowpea, Beans, Long beans, Cashew, Arecanut, Maize, Jak seeds ²² Take about five seeds from each type and soak them in water ²² Take the seeds out of water after about 24 hours carefully ²² Divide them according to number of cotyledons (seed leaves) inside the seed and add to Table 1.4 Table1.4 - monocot and dicot seeds Seeds with single seed leaf Seeds with two seed leaves Arecanut, Paddy, Maize Bean, Long Beans, Cashew, Gram, Green gram, Tamarind, Cowpea, Jak seeds You may have seen that certain seeds can be divided easily into two seed lobes whereas other seeds cannot be divided easily like that. There are two seed lobes. These seed lobes are called seed leaves. Seeds with two seed leaves are called dicot seeds. Some seeds cannot be divided into two seed lobes because they have only one seed leaf. This type of seeds are called monocot seeds. Germination Science | Plant Diversity 17 of monocot and dicot seeds are different from each other. Assignment 1.13 ²² Observe the plants/ trees found in your school garden and group them as monocots and dicots. Let's do Activity 1.9 to learn more about nature of those seeds. Activity 1.9 ²² Take bean seeds and paddy seeds which were soaked for about 24 hours and keep them on a wet cloth for about three days. Add a little bit of water every day. ²² When bean seeds are about to break into two, separate the seed lobes in one seed and observe them. ²² Plant other seeds in pots with wet soil. After few days you can observe that there are two leaves different from the other leaves of the germinated bean seeds. They are called seed leaves. ²² Seed leaves cannot be observed in paddy seeds. Because the seed leaves of them do not come out during germination. Figure 1.26 Germination of monocot Figure 1.27 Germination of dicot seed seed You have learnt about the variations of the basic parts of plant throughout this lesson. Now study the differences of basic parts of monocot plants and dicot plants that you have observed. Compare the differences you observed with Table 1.5. 18 Science | Plant Diversity  Table 1.5 Part Monocot plant Dicot plant Leaves Parallel venation Reticulate venation Flowers Three petals or its multiples Four/ Five petals or its multiples Seeds Only one seed lobe Two seed lobes Stem Not branched Branched Root Fibrous root system Tap root system Figure 1.28 A monocot plant Figure 1.29 A dicot plant Activity 1.10 ²² Create a model to show the basic differences between main parts of dicot and monocot plants that you have already observed. Now you must have a proper understanding about the vast diversity of members of the plant world, upon observing and studying morphological variations of them. The fieldbook that you prepared would display the diversity of plants very well. Science | Plant Diversity 19  Summary ²² Plants which produce flowers are called flowering plants whereas plants do not produce flowers are called non flowering plants. ²² The main parts of the flowering plants are roots, stem, leaves, flowers, fruits and seeds. ²² Although main parts of a plant usually perform one specific function, sometimes they are adapted for several other functions. ²² A vast variation can be seen among main parts of the plants. ²² Flowering plants can be divided into two groups as monocotyledonous (monocot) plants and dicotyledonous (dicot) plants. Exercise 1. The table below indicate several kinds of plants with numbers identified by a group of students in a field trip to a forest. Name of ʻDanʼ ʻMadu ʻKitulʼ Cashew ʻKottambaʼ ʻBeduruʼ Cycas Mimosa the plant ʻNavalʼ welʼ Number 2 3 4 4 2 1 10 12 of plant II. Display the data in a bar chart. III. What is the most abundant plant found in this forest? IV. Name a plant/plants in the above forest, that found with these features (a) A weak stem (b) An unbranched stem (c) No flower (d) A fibrous root system (e) Compound leaves (f) Fruits with fibrous outer layer (g) Having nodules 20 Science | Plant Diversity V. (A) Select a monocotyledonous and a dicotyledonous plant out of the plants given above. (B) Write one major difference of (a) leaves (b) Stem (c) roots and (d) seeds of above two plants. Technical Terms Monocotyledonous & talîcm;%S Ydl & J¸ Âzvø»z uõÁµ® Dicotyledonous & oaùîcm;%S Ydl & C¸Âzvø»z uõÁµ® Flowering plants & imqIam Ydl & §US® uõÁµ[PÒ Non Flowering & wmqIam Ydl & §UPõz uõÁµ[PÒ plants Gynoecium & cdhdx.h & ö£snP® Androecium & mqux.h & BnP® Petals & o,m;% & AÀ¼PÒ Corolla & uql=gh & AÀ¼ Ámh® Sepals & uKsm;% & ¦À¼PÒ Stigma & l,xlh & SÔ Style & lS,h & u®£® Ovary & äïn fldaIh & `»P® Venation & kdrá & |µ®£ø©¨¦ úkHdih Science | Plant Diversity 21