Question
why do roses grow thorns???????????????

Answer
Officially if you want to be considered very correct in your terminology then modified leaves are referred to as spines, modified branches are thorns and modified epidermal cells are prickles. In most cases, people simply refer to them as thorns or spines. Examples of a few plants that deploy these types of defenses include roses, raspberries and blackberries. Regardless of what we call them, structures such as thorns make it difficult for animals to come along and take a bite without a painful lesson. Before men started to cross roses, they used to grow like wild brambles along the ground and some grew like a large raspberry bush. No matter how they grew, the thorns served as protection.