Anatomy Of Flowering Plants - Secondary Growth

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If a dicot tree adds one distinct annual ring each year, approximately how old is a trunk showing forty clearly countable rings?

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Secondary growth in dicot trees produces visible annual rings, and NCERT explains how these arise and how they can be interpreted. The vascular cambium is more active in the favourable spring season, producing wide, light early wood, and less active in winter, producing narrow, dark late wood; one ring of early plus late wood together represents one year's growth. Therefore, counting the number of annual rings gives a direct estimate of the tree's age in years. With forty distinct rings and one ring formed per year, the trunk is about forty years old, so forty years is correct. Twenty years would require each ring to represent two years, which contradicts the one-ring-per-year rule. Eighty years would require two rings to form each year, which is not the normal pattern in seasonal climates. Ten years grossly underestimates the count of rings observed. As stated in NCERT Class 11, Chapter 6 (Anatomy of Flowering Plants), annual rings are used to estimate the age of a tree. A numerical sanity check confirms that forty rings at one ring per year equals forty years.

Anatomy Of Flowering Plants - Secondary Growth

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