Timber Plants · Botany

What are annual rings in timber mainly caused by?

  1. Seasonal differences in secondary xylem growth
  2. The daily opening and closing of the leaf stomata
  3. Formation of new root hairs during growth
  4. Seasonal production of new flower buds
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Correct answer: Seasonal differences in secondary xylem growth

Annual rings form because vascular cambium produces different types of secondary xylem during different seasons. Early wood and late wood together can mark one year of growth in many trees.

Difficulty: Medium Question 15 of 18

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