Why do roses have thorns? Protection?


Thorny rose – why would such a beauty hide under a prickly wall of thorns? In reality, it is not that simple, and if you were to look in botany textbooks you would find out that roses actually have no thorns…

There is no rose without thorns – they say. And it is true for now. Yes, we already have varieties that have very few thorns, or grow on older stems only, but there is always some prickly danger. A good example is the spiny-leaved rose(Rosa spinosissima) with unusual black rose hips. You can find this rose also in Central Europe – but only in warmer places.

Roses do not have thorns – they have prickles

True. I remember that my biology teacher caught many students not knowing the difference. To clarify, thorns are always formed from the buds of twigs or leaves. They are long and sharp and you cannot break them. On the other hand, prickles are formed from the upper layers of the plant tissue and you can break them off quite easily. Try it and you will see the difference. You can see “the real” thorns, for example, on gooseberry, acacia, sea buckthorn or barberry.

RosePhoto: Pixabay

So why roses have these thorny prickles?

It is not because roses fight hungry herbivores, this feature is just an extra bonus at best. Animals can graze and avoid thorns (prickles) very skilfully and thorns do not bother these evil herbivores at all.

To find out the real reason, we must look at the origin of prickly roses and where they grow naturally and that is in light deciduous forests. In a forest a free space is rather precious commodity, and all plants try to take as much free space as possible. So do roses but their stems are fragile and cannot grow very high – unless they find some good support. And it is the thorns roses use to get support from neighbouring plants. So, roses use thorns to climb and to get support. Simple.

Preview photo: Pixabay

Radek Štěpán

Gardening is my hobby, I have a lot of experience and I am happy to share it.


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