Plant Defenses: 8 Ways Plants Defend Themselves

Plant defenses are the way plants protect themselves from many threats. Unlike other beings, plants cannot move, run, or flee. But they are constantly under attack so they need to resort to different ways to defend themselves from many attackers.

Although plants lack critical thinking and movement like humans they do have a solid defense mechanism. Plant defenses include both physical and chemical ways to ward off the danger.

Disregarding plants as life forms can be a big mistake because they do also feel the pain and threat of getting destroyed. So in this article, we discuss some unbelievable plant defenses that help them protect themselves.

Induced & Constitutive Plant Defenses

Plants divide their energy between their growth and defense. So plant defenses come at the expense of energy that is required for their growth.

In certain environments like tropical forests, plants are constantly under attack. So to protect themselves the amount of toxic compounds are always high in the leaves. Therefore, plant defenses that are always “on” are called “constitutive” defenses.

On the other hand, plants that are not surrounded by many threats can increase or decrease their defenses. The plant defenses that are not always on high alert are called “induced” defenses. For example, newly informed leaves sometimes produce more trichomes, and many indoor plants use this defense system.

Different Plant Defenses

Sting

Many plant species like Urtica Dioica aka stinging nettle use trichomes or stinging hairs to protect themselves from intruders. The leaves and the stem of the common nettle are covered with glandular trichomes.

These hollow hair-like structures release chemicals like histamine that cause stinging-like sensations.

Stinging nettle should be handled with care as it can cause rashes on the touch.

Releasing Venom

The leaves of Dieffenbachia, also known as the dumb cane contain calcium oxalate crystals when chewed the leaves release these idioblasts into the mouth of predators.

This can result in paralysis or loss is speech hence the name “dumb cane”. Though this plant can cause such harm to human health it is widely used for ornamental purposes.

Inducing a Heart Attack

The foliage Digitalis Purpurea, or foxglove is as deadly as it is beautiful. The foliage of this plant contains a toxic called digitoxin that is lethal to both humans and insects and can possibly result in heart failure upon ingestion.

Due to this, foxglove has one of the most deadly plant defenses in the world.

Signaling To Birds For Rescue

Several plants like Strelitzia Reginae also known as bird-of-paradise flower use VOCs (volatile organic compounds) to signal birds that they are under attack.

The birds are attracted to its fruity scent and attack the pests that are harming the plants. This plant is native to South Africa and is used as a houseplant because of its attractive flowers.

African marigolds could be another example of such plant defenses that uses the help of birds to fend off pests.

Poison Nearby Plants

Several plants consider other plants as their enemy. In such situations, plants must defend themselves in order to survive.

For example, when the Black Walnut tree senses another plant growing in its range it releases a toxin called juglone to kill the intruder. The toxin is also used to fight off insects and other herbivores.

To humans, even a small amount of juglone can be toxic.

Camouflage

The amazing defense of Corydalis Hemidicentra makes it able to match the color of rocks it’s growing around. Scholars like Dr. Yang Niu said that these plants know how to make the right color by mixing various pigments.

We don’t have the exact idea of how these plants are able to change their colors but it is truly amazing to see such plant defenses just like animals.

Appear Dead

Plants like Mimosa Pudica, commonly known as the sensitive plant are very reactive to touch stimuli. Upon touch the leaves of this plants fold inwards and appear dead which makes it unappealing to many predators.

This is one of the most rapid in all of the plant defenses. The rapid release of water through specialized cells results in the quick response of the plant.

In addition to touch the leaves of this plant also folds in the dark and reopen again in daylight. This type of defense is said to startle many herbivores and prevent grazing.

Alert Each Other

Plant-Plant communication is another plant defense that uses VOCs to send a signal from one plant to another about any possible threat. When a plant is getting attacked by any insect it releases a mix of VOCs.

This triggers other plants to increase the amount of their defensive compounds. Plants use this type of communication to increase their chances of survival. This signaling is also used to communicate about weather conditions like drought or rainfall.

For example, Sagebrush when attacked by herbivores release VOCs that can trigger increased production of defensive compounds in neighboring plants.

Conclusion