Question

Growth rings (annual rings) are formed by activity of ?

• A. Cambium
• B. Xylem
• C. Phloem
• D. Both xylem and phloem

Answer 1

The correct option is A Cambium

In temperate woody plants, the activity of vascular cambium is seasonal. The cambium is less active in autumn. This difference in secondary xylem growth due to the cyclic seasonal changes result in the formation of alternate rings of autumn wood and spring wood. These two zones constitute an annual or growth ring.

Thus, the correct answer is option A.