Which tree tissue is primarily responsible for growth in diameter?

Which tree tissue is primarily responsible for growth in diameter?

• A. Cambium
• B. Xylem
• C. Phloem
• D. Bark

Answer: (A)

Growth in diameter comes from the vascular cambium, a thin layer of meristematic tissue between the wood (xylem) and inner bark (phloem). As the cambium divides, it adds new xylem on the inside and new phloem on the outside, producing more wood and bark and widening the trunk or branches with each growing season. This activity is called secondary growth, and it’s what gives trees their increasing girth over time. Xylem and phloem are produced by the cambium and serve their transport roles, while bark is the outer protective layer and isn’t the tissue driving the diameter increase.

Growth in diameter comes from the vascular cambium, a thin layer of meristematic tissue between the wood (xylem) and inner bark (phloem). As the cambium divides, it adds new xylem on the inside and new phloem on the outside, producing more wood and bark and widening the trunk or branches with each growing season. This activity is called secondary growth, and it’s what gives trees their increasing girth over time. Xylem and phloem are produced by the cambium and serve their transport roles, while bark is the outer protective layer and isn’t the tissue driving the diameter increase.