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CHAPTER – 7, GETTING TO KNOW PLANTS, •, , Plants are usually grouped into herbs, shrubs, trees, and climbers based on their height,, stems and branches., , •, , Classification of Plants on the of Growth Habit:, (a) Herbs: Have soft, green and week stems. Example: rice, wheat, maize, sunflower,, mint, etc., (b) Shrubs: They are bushy and have hard stems that do not bend easily. These are plants, with the stem branching out near the base. Example: lemon, china rose, jasmine,, Nerium, etc., (c) Trees: These are big plants which have a tall and strong stem (trunk). Stems have, branches in the upper part, much above the ground. Live for many years. Example:, mango, neem, banyan, coconut, etc., (d) Climbers: Have weak stems and cannot stand erect. They take support of other trees, and climb on them. Example: pea, grape, vine, etc., (e) Creepers: Plants which creep on the ground and spread out. Example: pumpkin and, watermelon., , •, , Classification of plants on the basis of their Life Cycle:, (a) Annuals: Plants whose life cycle is completed in the one season. These are generally, herbs. Example: wheat and mustard., (b) Biennials: Plants whose life cycle requires two seasons for completion. They are, generally herbs and rarely shrubs. Example: carrot, radish and potato., (c) Perennials: Plants whose life cycle runs for more than two seasons example: guava,, babul and palm trees., , •, , Parts of a Plants:, (a) Root system: It is the underground portion of the plant., (i), , Tap Root: It is the main primary root arises from lower end of the stem. A, number of tiny braches called secondary roots. Example: mustard, neem, rose,, etc.

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(ii), , Fibrous Root: A bunch of roots arises from the bae of stem. Example: wheat,, maize, etc., , Functions of root system:, (i), , Roots absorb water and nutrients from the soil., , (ii), , Roots help the plant to stand erect., , (iii), , Roots check soil erosion., , (iv), , Roots store food., , (v), , Prop roots offer extra support., , (b) Shoot system: The part of the plant which grows above the soil. It includes stems,, branches, leaves, flowers and fruits., (i), , Stem: Gives riese to a number of branches that bear leaves. The stem bears, leaves, flowers and fruits., , (ii), , Leaf: Leaf arises from the leaf base. A leaf usually has a petiole and a lamina., Parts of leaf:, (a) Petiole: Stalk of the leaf with which it joined to the stem., (b) Leaf lamina: The flat green portion of the leaf., (c) Veins: These are the network of small, narrow, tube-like structures on both, sides of the midrib present in the middle of leaf., , (iii), •, , •, , •, , Flower: It is the reproductive organ of the plant., , Function of Stem:, (i), , It provides support to plant., , (ii), , It bears important plant parts., , (iii), , It helps in transportation of water and food., , (iv), , Underground stems store food., , (v), , Thick and fleshy stems make food., , (vi), , Stem modified into tendrils give extra support for plants., , Function of Leaf:, (i), , Transpiration: Process of losign water by the leaves of a plant., , (ii), , Preparation of food by the process of photosynthesis., , Function of Flowers:, (i), , Help in reproduction., , (ii), , These become fruits that store food and seeds.

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(iii), •, , Modified flowers like cauliflower, broccoli are rich sources of vitamins., , Parts of Flower:, (i), , Pedicel: Stalk of the flower through which the flower is joined to the branch. It has, joined to the branch., , (ii), , Sepal: Small green leaf-like structures on the thalamus. They protect the flower., , (iii), , Petals: Brightly colored leaf-like structures present inside the sepals. Petals, attract the insects and help in the process of reproduction., , (iv), , Stamens: These are long, thin and needle-like structures. These are male organs, of the flower. It consists of two parts: Anther, Filament., (a) Anther: The swollen tip of each stamen that encloses in it a small powdery, substance called pollen grains., (b) Filament: Long stalk-like structure that joins the anther with thalamus., , (v), , Carpel: It is a flask-shaped organ in the centre of flower. It is the female organ of, the flower. It consist three parts: Style, Stigma and Ovary., (a) Style: Long thin tube-like structure which is swollen at the base., (b) Stigma: Small, round and sticky part of the carpel at the top of the style the, traps the pollen grains., (c) Ovary: Swollen part of carpel that contains ovules., , •, , 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., , •, , 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.