Why do roses have prickles?

Rose have prickles to protect themselves from predators. Prickles are similar to thorns, but are attached to the epidermal layer and can be easily removed from the plant.

Contrary to popular belief and literature, roses do not have thorns. Thorns are seen on vegetation, such as hawthorns, Japanese flowering quince and firethorn; the pointed spikes originate in the leaf axles on the main stem. Prickles on the other hand, are one of the most common defense mechanisms of many plants, especially garden plants, such as the rose. Although they appear less threatening than a thorn, they often can be more painful to the touch.