Animals have various ways to defend themselves. Skunks spray a stinky liquid at predators that try to attack them. Zebras run together in large groups to confuse predators. Prairie dogs run and hide in holes in the ground. Dogs bite.
Like animals, plants often need to defend themselves as well. After all, many animals are herbivores or omnivores. Herbivores eat only plants and omnivores eat both plants and animals. Defenses like poison, thorns, prickles, and stinging protect plants from the animals that would eat or damage them.
Thorns, Spines and Prickles
You wouldn't want to bite something that has thorns or prickles, right? It would hurt. Many plants have sharp defenses like thorns, prickles, and spines that protect them from being eaten by animals. Hawthorn trees have sharp thorns all over their branches. Cactus plants have spines. Rose bushes haves prickles.
Stinging plants like nettles have hairs with tubes that are filled with a stinging liquid. The tubes are delicate and break if touched. If an animal touches the plant, the tube breaks and the stinging fluid is injected into its skin. Stinging plants often have hundreds of these hairs that cover the leaves and stem. The chemicals in the stinging liquid can cause skin to become inflamed and irritated.
The 10 Most Common Poisonous Plants
These are the 10 most common poisonous plants according to Livescience.com:
Plants with weapons: Learn about plant defenses
Eating a poisonous plant can cause sickness or even kill. Eating just one leaf from a deadly nightshade plant can cause death. Every part of the plant is poisonous. The berries on a deadly nightshade plant look like edible berries and they even taste sweet. But they're so deadly just two to four berries could kill a child and ten to twenty could kill an adult.
When the Greek philosopher Socrates was sentenced to death for his beliefs the court gave him the right to pick how he would die. He choose tea made from the poisonous hemlock plant. Hemlock kills by causing stomach pains, vomiting, paralysis, and suffocation.
Rigid Cell Walls and Bark
Plants don't just need protection from animals. They also need protection from bacteria and other microorganisms that can cause disease. A plant's cell wall is strong and makes it difficult for pathogens (germs that can cause disease) to get inside.
Bark on trees serves the same purpose as human skin. It’s a protective outer layer. Bark helps to protect the cambium (layer underneath the bark) from damage caused by insects, weather, animals, and disease causing organisms. A tree can survive if some of its bark is stripped off. But if too much is removed, the tree will die.
© 2015 JoanCA
frozenink on July 08, 2015:
JoanCA (author) on July 08, 2015:
Thanks frozenink. I found another version of the video.
frozenink on July 06, 2015:
This is really a useful Hub for educating children. I like the inclusion of Bill Nye, but i think the video has already been removed.
Larry Rankin from Oklahoma on July 05, 2015:
A fascinating overview of the defenses of plant life.
Sheilamarie from British Columbia on May 04, 2015:
Nice approach on teaching kids about plants. Useful information.