As secondary growth proceeds, in a dicot stem, the thickness of
Both sapwood and heartwood increases
Both sapwood and heartwood remains the same
The correct option is D Both sapwood and heartwood increases The increase in lateral thickening is called as secondary thickening or secondary growth. This development takes place in stele (intrastelar secondary growth) and also in the cortex (extra stellar secondary growth). The elements of secondary xylem constitute wood. The xylem includes heartwood and sapwood. Hence, during secondary growth, both the sapwood and the heartwood increase in thickness.