Which tissue is responsible for girth growth in many woody plants?

Which tissue is responsible for girth growth in many woody plants?

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

Answer: (D)

The tissue that drives the widening of many woody plants is the cambium, a lateral meristem. The cambium sits between the xylem on the inside and the phloem on the outside. Its cells continually divide, producing secondary xylem (wood) toward the inside and secondary phloem toward the outside. This activity adds concentric layers and increases the stem’s or root’s circumference, which is what we recognize as girth growth. Cortex sits outside these vascular tissues and doesn’t drive this radial expansion, while xylem and phloem themselves are the products of cambial activity rather than the tissue doing the expanding.

The tissue that drives the widening of many woody plants is the cambium, a lateral meristem. The cambium sits between the xylem on the inside and the phloem on the outside. Its cells continually divide, producing secondary xylem (wood) toward the inside and secondary phloem toward the outside. This activity adds concentric layers and increases the stem’s or root’s circumference, which is what we recognize as girth growth. Cortex sits outside these vascular tissues and doesn’t drive this radial expansion, while xylem and phloem themselves are the products of cambial activity rather than the tissue doing the expanding.