5 surprising ways plants protect themselves 

Reflexes help humans defend themselves from danger. We can protect ourselves from potential threats because our brains can perceive them. However, have you ever wondered how plants without brains guard themselves? Although plants lack brains, they have an incredible defence system. Some plants have thorns or spines that keep herbivorous predators away while others contain chemicals that will make them sick or kill them. Despite being firmly rooted in the ground, plants are not just passive victims happy to watch as their lives are taken away. Let's learn a few of their defence mechanisms. 

Thorn 
Thorns are sharp stems or branches. Their defensive role is self-explanatory: They pierce anyone who touch! Remember where you may have seen one? On a cactus plant (Cactaceae).  

Prickle 
While Poison, an American metal band, wrote in their 1988 song that 'every rose has its thorn,' not a single rose has one. How so? Well, roses (Rosa) have prickles rather than thorns. In contrast to thorns, prickles are angular projections from a plant's epidermis (outer layer of tissue). Imagine them as sharp freckles. Here is an amusing fact. While certain predators are discouraged from preying on plants that have prickles, there are some that take advantage of this defence. Several kinds of planthoppers (green leafy insects) that are tiny enough to fit between the plants, suck up sap by mimicking their spiky look to ward off predators. 

Trichome 
To protect themselves from grazing, nettles and other plants develop spiky fur of pointy structures.  

These pointy structures are called trichomes. If you've ever had the bad luck of meeting a stinging nettle (Urtica dioica) (a plant with pointy leaves), you already know the potency of the small trichome in inflicting misery. What else? Some tropical nettles can kill you or permanently harm your nerves. Associated glands in certain plants, like the nettle, release poison into the trichome-induced wounds. 

Idioblasts 
Now let's look a little beneath the surface. Not every plant reveals its defence on the outside. If thorns, prickles, and trichomes serve as spears, idioblasts serve as landmines. Idioblasts are specialised cells that explode when the initial line of defence is breached. They contain various protective substances, such as pain-inducing chemicals and razor-sharp crystals. Common houseplant Dieffenbachia seguine has idioblasts that shoot calcium oxalate crystals into the mouths and subsequently release an enzyme resembling reptile venom. Bonus fact: Due to the potential for paralysis and subsequent loss of speech, it is also called a 'dumb cane.' 

Crypsis 
When touched, the Mimosa pudica, a sensitive plant, shuts its leaves, making them lifeless and unpleasant. This ability of a plant to avoid detection by other animals is known as Crypsis. These plants are frequently displayed in botanical gardens. The lasting proof that plants are alive comes from watching them respond in real time! You may witness how Mimosa closes its leaves by watching a YouTube video in slow motion.