Why Do Roses Have “Thorns?” (They Could Be Dangerous!)
Every rose has its thorns—or at least that’s how the song by Poison goes. But what are they really for? Is their only purpose to give gardeners scratches and cuts here and there? Or is there actually more to their prickly nature than most people are aware of?
The “thorns” on rose stems are technically called prickles and are formed to physically prevent animals from eating them. While garden rose varieties and cultivars have more thorns than landscape ones, excessive prickles are a result of rose rosette disease.
Roses don’t even actually have thorns. Sure, they have thorn-like growths along their stems but they are biologically different. Let me tell you all about it!
The Prickly Protection of Roses Against Animals
Prickles, confused for thorns, are sharp projections on rose canes that protect them from being eaten by herbivorous and omnivorous animals like insects and rodents.
Contrary to popular belief those razor-sharp spikes found growing along the circular stems—or canes—of roses are actually not thorns. I’ll elaborate on their differences later on.
The correct term for these spiky protrusions on roses is prickles!
In botany, prickles refer to the irregular, superficial, sickle-shaped growth between the nodes on plants’ stems. They are believed to either form on a plant’s outermost cell layer or the specialized hairs that grow on that layer.
Another cool thing about rose prickles is that grow are thicker and denser from the base of roses and similar plants compared to those by the middle and top portion of the stem.
This may have something to do with the fact that these woody prickles serve as the first line of defense for roses. Unlike animals and humans, plants can’t actively hide or fight against potential predators.
Check out other beautiful blooms in our article on flowers perfect for dates!
Because of the prickles on rose canes, it will be painful and almost impossible for animals to chomp off chunks from spike-filled bushes. Even smaller animals will have a difficult time trying to climb a rose because of the prickles.
Having more prickles by the bottom half—or third—of rose canes prevents animals from up-rooting them. Even if some try to eat roses, they’ll likely stay away after their first attempt.
How are Prickles, Thorns, and Spines Different From Each Other?
Prickles are superficial growth on stems, whereas thorns and spines have vascular tissues. More specifically, thorns are modified branches while spines are modified leaves.
One thing that prickles, thorns, and spines have in common is that getting your skin caught by them can be very painful. They can be pretty tough to cleanly dislodge from your skin.
At best, you’re just doing it to have a shallow scratch or cut. But if you notice any swelling around your prickle wound, I’d be worried—more on why in a later section!
Their main differences are based on which part of a plant they grow from and what they’re primarily made of.
Prickles grow out of the epidermis of plant stems. Thorns normally grow from nodes, where leaves usually emerge from, on a plant’s stems. Meanwhile, spikes develop from different parts of a plant’s leaves.
Besides that, out of the three, only prickles don’t have vascular tissue—which are crucial parts involved with water and nutrient transfer throughout the plant. As a result. thorns and spines are often more difficult to remove from plants.
Examples of plants with prickles, thorns, and spikes include devil’s walking sticks, firethorns, and cacti, respectively.
Learn why cacti grow spines instead of regular leaves!
Why Do Some Roses Have More Thorns Than Others?
Some types of roses simply have more thorns than others and vice versa. However, abnormal growth of too many prickles (“thorns”) is a sign of rose rosette disease.
All in all, more than 6 thousand cultivars and varieties of roses exist throughout the world. So it’s only to be expected that they’ll have a few differences—including the number of prickles they sport on their canes.
For the most part, roses have numerous prickles on their canes for protection. But some types grow fewer razor-sharp prickles as a result of breeding—more on this in just a bit!
However, a sick rose bush could develop immensely prickly thick canes which make them pretty much impossible to hold without getting hurt—even with padded leather gloves!
Rose rosette disease (RRD), to be more precise, results in excessive prickle growth in affected rose bushes. It was first identified early in the 1940s. But its cause—a virus called Emaravirus sp.—was not discovered until 2011!
This disease is primarily spread by microscopic eriophyid mites (Phyllocoptes fructiphilus). A less familiar cause of spreading is grafting. So remember to disinfect your plant tools.
Unfortunately, there is still no cure for rose rosette disease. All parts of affected plants, including the roots, must be completely discarded to prevent further spread.
Which Roses Have More Thorns Than Others?
Traditional garden roses normally have more prickles (thorns) than landscape rose varieties and cultivars. Hybrid tea, floribundas, grandifloras, and climbing roses are bushy roses with many prickles.
Even though these rose groups are mostly cultivated for their showy flowers, they don’t develop fewer thorns.
Garden roses with more prickles than landscape roses include
- All That Jazz
- Angel Face
- Betty Prior
- Color Magic
- Dainty Bess
- Double Delight
- Elegant Beauty
- Eye Paint
- Folk Lore
- French Lace
- Garden Party
- Ivory Fashion
- Madame Violet
- Perfect Moment
- Pink Parfait
- Princess de Monaco
- Razzle Dazzle
- Red Gold
- Sheer Bliss
- Summer Dream
- Sun Sprite
- The Fairy
- Touch of Class
- White Lightnin
So if you’re planning to grow some at home, you need to consider if you’re okay with having such prickly plants at home—especially if you have children and pets at home!
What Types of Rose Have Fewer Thorns Than Others?
Landscape rose varieties and cultivars normally have fewer prickles (thorns) than common garden roses. Such shrubby roses can also be grown as ground cover.
Below are some landscape rose species with fewer prickles than garden varieties
- Boursault roses (Rosa alpina)
- Chinese or Bengal roses (Rosa chinensis)
- French roses (Rosa gallica)
- Redleaf rose (Rosa glauca)
- White roses of York (Rosa alba)
In particular, the French rose cultivar called Mundi and redleaf roses have little to no prickles. Some even describe them to be almost without thorns!
Shrubby landscape roses also require less pruning and don’t need regular deadheading, unlike traditional garden roses. They can even flower throughout the year!
Check out other gorgeous blossoming plants in our article on 45 colorful daisies!
Any of these will be perfect if you want to grow rose bushes that have fewer chances of hurting you or your loved ones while spending time in the garden.
Are Rose Thorn Wounds a Problem for People?
Despite not containing poison, wounds from rose prickles (thorns) can not only be painful but also dangerous due to fungal spores. Immunocompromised individuals are more likely to develop complications and severe sporotrichosis.
Roses aren’t poisonous. Even their thorny prickles are devoid of any toxic compound that can put our health at risk. But “thorn” wounds aren’t as harmless as many people think.
You see, fungal spores exist all around us. These things easily land on both organic and non-organic materials. In other words, spores can also land on rose prickles.
If you’re unfortunate, a fungus called Sporothrix schenckii and other closely-related fungi could enter a wound made by rose bush prickles. This will result in sporotrichosis—also known as the rose gardener’s disease.
A small bump is the first sign of a rose gardener’s disease. It will appear 1–12 weeks after exposure to S. schenckii. When left untreated, this can grow bigger—resembling a boil—and multiply.
More often than not, this results in skin infection, especially with shallow scrapes and cuts on the hands and arms from rose prickles.
However, this condition can also severely affect a person’s lymphatic channels, lungs, kidneys, joints, bones, or even one’s central nervous system!
So if you get wounded while tending to your rose bushes, go to the nearest hospital or clinic to get it looked at immediately. Don’t wait for things to get worse getting medical care!
Treatment and Prevention for Rose Gardener’s Disease.
Rose gardener’s disease is primarily treated with antifungal medicine which may need to be regularly taken for 3–12 months. It’s also best to wear arm-length thick leather gardening gloves while taking care of rose bushes and shrubs.
You could try out home remedies for pain relief but that’s not going to let you heal completely.
To be clear, though, you need a prescription for antifungal medications that can effectively treat the rose gardener’s disease. So you need to see a health professional.
Oftentimes, what they’ll prescribe is an oral antifungal like potassium iodide or itraconazole. If you’re pregnant, they’ll likely give you something different. You might also need to get a tetanus shot. In severe cases, surgery may be needed.
Also, you should invest in high-quality, heavy-duty, thick leather gloves that go up to your elbows. Getting a thorn-proof glove like the one below from Amazon will serve you well.
Make sure to check the direction your rose prickles grow too.
Roses commonly have thorns pointing down to the ground. So instead of moving your hands upward, carefully move your hands downward instead. Doing so will lessen the likelihood of you getting snagged by these sharp prickles.
Using a gardening sheer or lopper with long handles will also lessen the need to get your hands deep into your rose bushes while pruning and up-keeping them.
What happens if you cut thorns off roses?
Cutting prickles (thorns) off roses won’t significantly damage the plant since they don’t contain vascular tissue. However, the wounded parts of rose canes can put the plant at risk of deterioration, contamination, and disease. Cut roses that have had their prickles removed won’t last as long as those with retained prickles.
Are roses the only flowering plants with thorns?
Roses aren’t the only plant to grow thorn-like protrusions. Plants that develop prickles, thorns, and spines include aloe veras, blackthorns, bougainvillea, Californian fuchsias, crown of thorns, devil’s walking sticks, firethorns, flowering quinces, hawthorn, holly, honey locusts, natal plum, Oregon grapes, porcupine tomatoes, and sea buckthorns.
Summary of Why Roses Have Thorns
Because they have limited means of protecting themselves, roses grow prickles—commonly mistaken for thorns. These sharp protrusions along their stems prevent animals from eating and destroying them.
Bushy common garden roses like the hybrid tea Cayenne and grandiflora Angel Face roses typically have densely packed (“thorns”) prickles. Shrubby landscape roses like French Mundi roses have far fewer prickles. Abnormally prickly thick rose canes, however, are a sign of rose rosette disease.
Superficial rose “thorn” wounds are rarely ever life-threatening. But if Sporothrix schenckii fungal spores are present on the surface of rose plants, they can enter one’s body through the wound. This can result in mild to severe cases of rose gardener’s disease or sporotrichosis.
- “Do roses have thorns, spines or prickles?” by Anita Finkle in the New York Botanical Garden
- “Of Thorns, Spines and Prickles” by David Trinklein in the Integrated Pest Management, University of Missouri
- “Rose Rosette Disease” by Jennifer Olson, Eric Rebek, and Mike Schnelle in Oklahoma State University
- “Grasp the thorn!” by Kamille Hammerstrom in Agriculture and Natural Resources, University of California
- “Roses” by S. Bale, R. Durham, T. Phillips, L. Townsend, and N.A. Ward in University of Kentucky College of Agriculture
- “Armed Rachis Can Leave You Bloody” by Rich Baer in The American Rose Society
- “Sporotrichosis” by n/a in Centers of Disease Control and Prevention