The rose is one of the world’s most cultivated flowering shrubs, instantly recognizable by its delicate blooms and sharp defenses. While the saying suggests every rose has a “thorn,” the answer to whether all rose bushes possess these sharp structures is nuanced. Not all roses are equally armed, and the common term “thorn” is botanically incorrect. Understanding this distinction leads to a deeper look at the plant’s structure and specific garden varieties.
Understanding Rose Prickles
What most people call a rose “thorn” is technically a prickle, a distinction based on the structure’s physical origin. True thorns, like those on a lemon tree, are modified stems or branches deeply connected to the plant’s vascular system. They originate from a node, the point on the stem where a leaf or branch typically grows.
Prickles are outgrowths of the epidermis, the outermost layer of the plant’s tissue, and the underlying cortex. This superficial connection means they lack the internal vascular bundles found in true thorns. Because they are only attached to the skin layer, a rose prickle can often be snapped or scraped off cleanly without tearing the stem’s wood.
The Biological Purpose of Prickles
The development of these sharp outgrowths serves two primary biological functions that aid the rose’s survival in the wild. The most obvious role is as a mechanical defense mechanism against herbivory. The dense, sharp points deter large grazing animals, such as deer or rabbits, from consuming the stems and leaves, protecting the plant’s vegetative growth.
The second function is physical support, particularly for roses with a climbing or scrambling growth habit. The prickles on these varieties are often hook-shaped, allowing the long, flexible canes to catch and hold onto surrounding vegetation. This ability to anchor helps the rose bush climb upward through the forest undergrowth, ensuring its leaves and flowers can reach sunlight for photosynthesis.
Rose Varieties with Few or No Prickles
Despite the prevalence of prickles on most wild and hybrid roses, specific cultivars have been bred or naturally possess smooth stems. Truly prickle-free roses are those where the genetic trait for prickle development has been naturally or intentionally suppressed. The popular Bourbon rose ‘Zephirine Drouhin’ is a genuinely thornless variety, producing flexible canes ideal for training on arches or fences.
Other near-thornless examples include the ‘Lady Banks Rose’ (Rosa banksiae), known for its vigorous, smooth-caned growth. Cultivars like ‘Kathleen Harrop’ and ‘Smooth Angel’ also exhibit significantly reduced or non-existent prickles. These smoother varieties, often older garden roses or climbers, are easier for gardeners to prune and handle.