To quote Guns ‘N Roses, “Every rose has it’s thorn” but actually rose thorns are called “prickles”. Thorns on other plants and trees are made up of the same materials as the plant. Those thorns are deeply embedded in the woody structure of the plant, and can’t be broken off easily. Rose thorns by definition, can’t really be thorns at all, because they are made up of small, sharp outgrowths of the rose’s outer layers. Unlike a thorn, a prickle can be easily broken off the plant because it is really a feature of the outer layers rather than part of the wood. Roses grow prickles as a form of defense against predators.
However, not every rose has prickles. There are a few varieties that have little to no prickles on them. These are great to plant along walkways, or in gardens.