Why do some plants have thorns?

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You’ve probably noticed that certain plants, like roses and cacti, have prickly thorns that hurt you if you accidentally touch them! – Ouch! Why do these plants need these scratchy spikes? 

The answer depends a little bit on which plant you’re talking about. When it comes to roses, the thorns are mostly there for defense – an animal won’t eat a rose bush if it’s going to get all scratched up during the meal! 


Cacti also have their spikes for this same reason, but also for another important reason: The thorns on a cactus are like their replacement for leaves! This helps them to lose less water in the desert heat. And, for cacti with enough spines, they also sometimes help to provide the plant with some shade


by   (whyzz writer)
  • Exploration

    Get planted!

    Take a look at some of the plants in your yard at home or in a nearby park or garden, making sure to be careful of plants like poison ivy or thorny bushes that could hurt you, and remembering not to pull off any stems or leaves from plants that are growing.  

    What are some of the interesting features that you notice from plant to plant? For example, are all of the plants the same shade of green, or are some of them darker or lighter than others? What about the shapes of the leaves? Think about the similarities and differences between each!

    When you get home, draw some pictures of the different things you saw!

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