Download Plant Parts and Their Functions: Roots, Stems, and Leaves - Prof. Nmh and more Slides Agricultural economics in PDF only on Docsity! LESSON 6 PLANT PARTS AND ITS FUNCTION In monocotyledonous plants, the primary root is short lived and is replaced by a large number of roots. These roots originate from the base of the stem and constitute the fibrous root system. In majority of the dicotyledonous plants, the direct elongation of the radicle leads to the formation of primary root which grows inside the soil. It bears lateral roots of several orders that are referred to as secondary, tertiary, and so on. The primary roots and its branches constitute the tap root system. THE ROOT IS COVERED AT THE APEX BY A THIMBLE-LIKE STRUCTURE CALLED THE root cap. It protects the tender apex of the root as it makes its way through the soil. TAP ROOTS OF CARROT, TURNIP AND ADVENTITIOUS ROOTS OF SWEET POTATO, GET SWOLLEN AND STORE FOOD. In some plants, roots arise from parts of the plant other than the radicle and are called adventitious roots. SIMILARLY, THE STEMS OF maize and sugarcane have supporting rootscoming out of the lower nodes of the stem. These are called stilt roots. Hanging structures that support a banyan tree are called prop roots. Underground stems of potato, ginger, turmeric, zaminkand, colocasia are modified to store food in them . STEM TENDRILS WHICH DEVELOP FROM AXILLARY BUDS, ARE SLENDER AND SPIRALLY COILED AND HELP PLANTS TO CLIMB SUCH AS IN GOURDS (CUCUMBER, PUMPKINS,WATERMELON) AND GRAPEVINES. AXILLARY BUDS OF STEMS MAY ALSO GET MODIFIED INTO WOODY, STRAIGHTAND POINTED THORNS. THEY PROTECT PLANTS FROM BROWSING ANIMALS. SOME PLANTS OF ARID REGIONS M ODIFY THEIR STEMS INTO FLATTENED (OPUNTIA), OR FLESHY CYLINDRICAL (EUPHORBIA) STRUCTURES. THEY CONTAIN CHLOROPHYLL AND CARRYOUT PHOTOSYNTHESIS. UNDERGROUND STEMS OF SOME PLANTS SUCH AS GRASS AND STRAWBERRY, ETC., SPREAD TO NEW NICHES AND WHEN OLDER PARTS DIE NEW PLANTS ARE FORMED A TYPICAL LEAF CONSISTS OF THREE MAIN PARTS: LEAF BASE,PETIOLE AND LAMINA. THE PETIOLE HELP HOLDS THE BLADE TO LIGHT. LONG THIN FLEXIBLE PETIOLES ALLOW LEAF BLADES TO FLUTTER IN WIND, THEREBY COOLING THE LEAF ANDBRINGING FRESH AIR TO LEAF SURFACE. THE LAMINA OR THE LEAF BLADE IS THE GREEN EXPANDED PART OF THE LEAF WITH VEINS AND VEINLETS. THERE IS, USUALLY, A MIDDLE PROMINENT VEIN, WHICH IS KNOWN AS THE MIDRIB. VEINS PROVIDE RIGIDITY TO THE LEAF BLADE AND ACT AS CHANNELS OF TRANSPORT FOR WATER, MINERALS AND FOOD MATERIALS. LEAF VENATION- THE ARRANGEMENT OF VEINS AND THE VEINLETS IN THE LAMINA OF LEAF IS TERMED AS VENATION. Modification of Leaves Leaves of certain insectivorous plants such as pitcher plant, venus-fly trap are also modified leaves for their food. Do Plants Also Respire? PARTS OF THE
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THE FLOWER: is the reproductive unit in the angiosperms. It is meant for sexual reproduction. Androecium and gynoecium are reproductive organs. When a flower has both androecium and gynoecium, it is bisexual. A flower having either only stamens or only carpels is unisexual. Aestivation: The mode of arrangement of sepals or petals in floral bud with respect to the other members of the same whorl is known as aestivation. PROCESS OF SEXUAL REPRODUCTION IN PLANTS POLLINATION IDENTIFY THE SEXUAL PART OF THE
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The Fruit- The fruit is a characteristic feature of the flowering plants. It is a mature or ripened ovary, developed after fertilization. If a fruit is formed without fertilization of the ovary, it is called a parthenocarpic fruit. The ovules after fertilization, develop into seeds. Word Scramble Activity In this activity, you'll check your knowledge regarding the structure of androecium and gynoecium. Guidelines: For this activity, study the scrambled letters and try to unscramble or rearrange the letters to form a word or phrase that fits the given clues NSMTEA STAMEN IGNYMOEUC GYNOECIUM LITZETNIIFRAO FERTILIZATION CNMRIEOAUD ANDROECIUM 1. Flowers with both androecium and gynoecium are called? (a) Bisexual flowers (b) Anther (c) Stamens (d) Unisexual flowers 2. It is refers to the arrangement of sepals and petals in the bud condition is called : (a) Pollination (b) Position (c) Fertilization (d) Aestivation NOITOLAINPL POLLINATIO N
