Why do Roses have Thorns?

I love to grow roses in my garden and often use them for various purposes upon harvesting the flower bulbs, but I rarely enjoy being stung by their nasty thorns.

I am sure other gardeners and decorators would feel the same about this nuisance.

However, roses have thorns for a vital purpose, including survival and protection from possible predators.

Roses naturally grow thorns to clamber over other plants and rise taller to reach the full sunlight. They also protect the flower from small animals, predators, and pests attracted to fragrant flower bulbs. 

Reine des Violets
Reine des Violets is one of the thornless rose species (Source: Wikimedia)

Although it keeps away predators, the thrones can still be a nuisance to growers, gardeners, and decorators.

Take a look at why roses grow out thrones and whether you could easily find rose species without one for your garden.

But first, let us tell you that the pointy parts you see on the rose stem are not thorns but simply prickles.

Thorns vs. Prickles

People often call these rose thorns, but they are called prickles. Thorns and prickles may look similar, but they are pretty different.

If you wonder, thorns are a harder growth on the plant while prickles are comparatively softer, so you can break them easily.

According to Opuntiads.com, Prickles are a sharp outgrowth from the epidermis or bark, while a thorn is a modified stem and can be recognized because a leaf subtends it.

ThornsPrickles
Modification of stemModification of cortex and epidermis
Stiff and strong, comparatively challenging to breakSoft and pointy, relatively easy to break
Examples: Bougainvillea, Natal Plum, and PyracanthaExamples: Roses and Silk floss tree

Although slightly different, thorns and prickles have one thing in common.

They are intended for mechanical defense against small animals.

Hungtington points out that spines, thorns, and prickles are surprisingly different structures, even though they all serve a similar purpose.

Rose prickles derive from epidermal and sub-epidermal layers under the stem, providing a protective barrier against mechanical injury.

The sharp prickles on the stalk of roses grow almost 0.39 inches long and arched downwards.

Rose Prickles
A sample of Rose Prickles (Source: Wikimedia)

However, unlike thorns found in plants like Cactus, rose prickles completely lack microscopic vessels that conduct sugar and water throughout the plant.

Therefore, pointy prickles found on roses primarily appear for physical purposes such as clamping and mechanical defenses.

Why do Roses have Thorns?

According to Native American folklore, roses were originally thornless plants that predators frequently fed upon.

Fed up by this, roses decide to plead Nanahboozoo, a mystical being, who gave them thorn-like prickles to keep predators away.

Although it sounds fascinating, roses do not grow thorns.

Instead, they grow prickles that start from the epidermis or cortex of the plant stem.

Here are some compelling reasons why beautiful plants like roses grow out nasty prickles.

1. For Clamping Onto Other Plants

Not many growers know this, but rose prickles originally served a vital purpose of clamping over other plants to rise further.

The sickle-shaped prickles enable rose bushes to hang onto surrounding vegetation further up and monopolize sunlight.

The sharp extensions clamp over other plants to rise and increase the surface area to get maximum sunshine for photosynthesis.

As a result, the roses often blossom quicker than other flowering plants and have a richer color and fragrance.

Prickles on a rose stem
Prickles on a rose stem (Source: Wikimedia)

Therefore, prickles indirectly help the rose get more sunlight and a rich food supply necessary for its growth.

2. For Mechanical Defense

Roses originally grew on wild terrains, making them an easy forage for predators; hence, they started producing prickles to protect themselves from predators.

Roses start using their prickle’s mechanical defense against predators and other essential purposes.

These predators mainly include small animals like rabbits, squirrels, and crawling animals like insects from crawling upwards towards the flower buds.

The downward-facing prickles provide exceptional protection against bugs who intend to suck delicious flower sap.

The prickles also protect against large animals often attracted by their strong fragrance.

3. To Redirect Watering

It may come as surprising, but these downwards directions of the spines help to redirect water to the roots.

The downward curve of the prickles quickly redirects water coming from above to the root in the form of water droplets.

Therefore, they may indirectly help provide more water straight to the root system, especially during the dry season.

Do all Roses have Thorns?

It is so usual to see rose bushes with prickles that it may seem amusing if you happen to see without one.

Did you know there are over 30,000 varieties of roses in the world, and only a handful of them are without prickles?

Some hybrid roses are primarily grown for non-prickles, including climbing, English, Grandiflora, and hybrid tea species.

Thornless roses are often a result of a natural mutation that results in a hybrid plant. Their varieties include:

1. Thornless Climbing roses

Climbing roses are mutated varieties of bush or hybrid tea roses. They are known for extra-long canes that continue to increase.

Luckily, some climbing rose species are thornless, which can grow up to 12-feet and produce large pink blooms with a heavy scent.

Zépherine Drouhin
Zépherine Drouhin (Source: Wikimedia)

2. Thornless English roses

English roses are hybrid rose species introduced in 1969 by the English rose hybridizer David Austen.

Also known as David Austen Roses, these species combine the best elements of old and modern roses.

3. Thornless Heirloom roses

Heirloom roses are a hybrid variety of old roses developed around 1867, which tend to grow taller than modern hybrids and become bushier each year.

These are easy to grow garden roses since they are open-pollinated (pollinated by bees).

4. Thornless Hybrid Tea Roses

Hybrid tea roses were produced by cross-breeding two different rose varieties in 1867.

They manage to grow from 3-7 feet tall and 3-5 feet wide, but they require USDA hardiness zone 5-9 to grow appropriately.

Hybrid Tea Rose
Hybrid Tea Rose (Source: Wikimedia)

Top 10 Thornless Roses

The prickles can become a nuisance when you grow roses for decorations such as wall clampers.

You should labor to cut off all the prickles and ensure that you do not accidentally touch the tip.

Therefore, it is wise to choose thornless rose varieties that are safe to touch and equally fragrant.

Rose/USDA ZoneFeaturesImage
Irene Marie Miniature Roses (USDA Zone 5-9)1. They grow about 4-6 inches and have blooms lesser than an inch.

2. Blossoms are bright yellow and bold orange with a strong fragrance.
Amadis Thornless Rambler (USDA 6b-9b)1. A hybrid thornless rose perfect for decoration as Arbors and Pergolas in the garden.

2. They grow up to 5.5 meters and give out deep crimson-purple blossoms.
A Shropshire Lad (USDA 4 and above)1. Endemic to David Austin English climbing rose that can grow 4-6 feet.

2. The bloom size is 4-5" and produces a pink and peach blend of color with a fruity fragrance.
Blue Magenta (USDA 5-9)1. Produces rich blue to violet to dark purple shades and grows up to 10-feet tall.

2. Produces flowers once and gives out a mild fragrance.
Chloris (USDA 3-9)1. It grows 4-7 feet tall and gives out 2-3" pale pink blossoms with a sweet-smelling fragrance in summer.
Cinderella Miniature (USDA 5 or more)1. A miniature rose species known for the signature white to pink blossoms.

2. The blossoms are white in summer and appear light pink in early spring.
Rosa Goldfinch (USDA 6b-9b)1. They grow in a large cluster and give yellow to white blossoms, and climb up to 10-feet.

2. Bloom from early spring to late summer but are less vigorous.
Leander Hybrid Tea Rose (USDA 5b or more)1. They can quickly grow 7-14 feet and give out apricot blend blossoms throughout spring and summer.

2. As tea rose, they need particular attention to get their full height and fruity fragrance.
Rosa Lykkefund (USDA 5 or more)1. It is a rambler rose species first introduced in 1930 by Aksel Olsen.

2. They grow from 18-20 feet and 15 feet wide and give out white blend blossoms in clusters.
Reine des Violettes (USDA 4-9)1. They are recurrent bloomers who produce violet-colored blossoms and give out a pleasant fragrance.

2. They can easily climb up to 8-feet and become bushier each year.
Reine des Violets

FAQs About Roses

Here are the answers to some of the frequently asked questions about roses, including thornless roses

Should you Remove Prickles from Roses?

Do not remove prickles from live roses as it may reduce their lifespan and invite other problems.

Cutting the prickles will make a wound on the rose stems, causing a loss in moisture and excess dehydration.

The holes on stems will also be the entryways for bacteria and germs.

However, you could remove the prickles once you harvest the flower for decoration.

Are Prickle-less Roses Entirely Thornless?

It may depend on the species of thornless roses.

While some roses are entirely thornless, some may still grow soft prickles under certain growing conditions.

As prickles are natural to rose species, you cannot eliminate prickles.

Thornless roses are hybrids introduced in the latter part of the 18th century for decorative purposes.

Are Rose Thorns Poisonous?

Although rose prickles are not poisonous, they are undoubtedly harmful.

When the sharp prickles penetrate your skin, they can pass foreign elements, including bacteria, fungi, and garden chemicals.

These substances can cause severe infection and illness, including sporotrichosis, plant-throne synovitis, and mycetoma.

When you notice tiny bumps on the infected site getting more significant and more prominent, you should immediately contact your physician for antifungal medication.

Do Rose Thorns Grows Back?

Not really. Rose thorns are part of the stem’s skin or epidermis, unlike the cactus thorns that grow back after a while.

When you remove the prickles, they are gone forever.

Therefore, you should be wary about removing prickles from the live plants as they can deteriorate rose stems, even leading to bent-neck.

Can you Grow a Rose from a Thorn?

Growing a rose from a thorn is practically impossible because thorns are simply an overgrowth of stems.

The thorns lack any vegetative part that grows roots like stems, leaves, and root systems.

Therefore you can avoid trying to propagate rose out of a thorn.

Rosa Lykkefund
Rosa Lykkefund (Source: Wikimedia)

Conclusion

Roses are easy to care for as long as you provide plenty of sunlight, warm temperature, 60-70% humidity, and occasional plant food.

Luckily, thornless roses can grow and maintain the same conditioning as other rose species.

If you are particular about thornless roses, do not forget to pick the suitable species mentioned in the table above.

However, be careful about picking suitable thornless rose species from the grower like David Austen before planting them in your garden.

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