“Plants may go in for chemical warfare, with leaves that are WorldMags.net ENVIRONMENT unpalatable or even poisonous”
Cacti are infamous for their spiky exterior that defends their water stores
Plant defences explained The plant kingdom has evolved some canny ways to see off a variety of threats Leaves are vital to the survival of plants. They catch the sunlight that plants use to power food production from oxygen and water in the process called photosynthesis. Stems hold the leaves in a position that maximises the light they catch, much like an array of green solar panels. Anything that damages the leaves or stems reduces the amount of sunlight the plant can collect, slowing its growth and impacting on the plant’s overall health. Oddly, too much sunlight can damage plants too. Chlorophyll, the green chemical which reacts with sunlight in photosynthesis, is easily
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damaged by high intensities of direct sunlight. Plant cells therefore contain chemicals which act like sunblock, letting in just the right amount of light for photosynthesis. Plants that always grow in shady woods don’t need sunblock, but they may die if we replant them into sunny gardens. Drought also damages plant growth, because the leaves of a wilted plant are not best arranged to catch the Sun – so getting enough water is essential. However, the main threat to plant photosynthesis is from animals that eat the leaves or stems. Plants therefore invest a lot of energy in keeping grazers away. Some plants
use different kinds of armour. Their leaves might have a tough, waxy coat that makes leaves difficult to eat, or a beard of hairs to stop insects settling on them. Other defences might include their stems and leaves, which may have spines or prickles that make it uncomfortable to eat the leaves or even get too close. Many plants also go in for chemical warfare, with chemicals in their leaves that are unpalatable or even poisonous to grazing animals. A few species can also cheat; they don’t produce poisons themselves but instead look like other plants that animals know are toxic, and so avoid getting eaten by proxy.
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