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Q. In higher plants, the Secondary Growth refers to:
1. Development of flowers and fruits
2. Development of new branches after the plant starts flowering
3. Formation of secondary tissues by the activity of lateral meristem
Choose the correct option from the codes given below:

  • (A) Only 1 & 2
  • (B) Only 2 & 3
  • (C) Only 3
  • (D) 1, 2 & 3
  • Correct Answer - Option(C)
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Explanation by: Admin

Secondary growth is the growth that results from cell division in the cambia (see below), or lateral meristem, and that causes the stems and roots to thicken. Primary growth is growth that occurs as a result of cell division at the tips of stems and roots, and that gives rise to primary tissue. Secondary growth occurs in most seed plants, but monocots usually lack secondary growth. If they do have secondary growth, it differs from the typical pattern of other seed plants. In many vascular plants, secondary growth is the result of the activity of the two lateral meristems, the cork cambium and vascular cambium. Arising from lateral meristems, secondary growth increases the girth of the plant root or stem, rather than its length. As long as the lateral meristems continue to produce new cells, the stem or root will continue to grow in diameter. In woody plants, this process produces wood. Secondary growth results in an increase in diameter. Obstructions, both foreign objects such as this metal post, and parts of the plant, such as stubs of limbs, can be “swallowed” by continued growth. Because this growth usually ruptures the epidermis of the stem or roots, plants with secondary growth usually also develop a cork cambium. The cork cambium gives rise to thickened cork cells to protect the surface of the plant and reduce water loss. If this is kept up over many years, this process may produce a layer of cork. In the case of the cork oak it will yield harvestable cork. Secondary growth also occurs in many non-woody plants, e.g. tomato, potato tuber, carrot taproot and sweet potato tuberous root. A few long-lived leaves also have secondary growth.

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