What observation indicates that the thorns on a rose bush are modified stem?

Question

Quizplus · Accepted Answer

The arrangement of vascular bundles in a ring is a characteristic of stems. Since the thorns on a rose bush have this arrangement, it suggests they are modified stems. The presence of stomata, a centrally located vascular bundle, and a cuticle are not specific characteristics of stems and do not directly indicate that the thorns are modified stems.

What Observation Indicates That the Thorns on a Rose Bush