Self-defense

Needlelike crystals line the blue agave’s leaves, making them an unpleasant mouthful. Animals can run from their predators, but plants have no way of escaping hungry plant eaters. Instead, they have developed some clever ways of making themselves look and taste as unappealing or dangerous as possible, encouraging animals to look elsewhere for a meal. Plant defenses range from spiky thorns to toxic chemicals.

Spiky leaf edges protect these succulent leaves.

Silver-gray crystalsCamel thorn

Fully developed thorns may grow up to 2 1⁄4 in (6 cm) long.

Tea leaves contain tannin, a bitter-tasting chemical that deters animals from eating them.

Spines on the stem protect the plant from hungry animals.

These woolly leaves are difficult for insects to munch.

These swollen parts provide hollow homes for ants that help ward off predators, protecting the plant.

To deter predators, some plants, including the camel thorn, produce sharp branches called thorns, while others, such as gorse, make sharp leaves known as spines. Prickles are extensions of the stems of plants such as roses. Another plant defense strategy is the use of chemicals. Plants, such as tea, common milkweed, and blue agave, produce nasty-tasting or irritating chemicals to put off any animal that takes a bite. The spots on passion flower leaves are a clever defense called mimicry—the plant’s leaves pretend to be infested by butterfly eggs, which deters real butterflies from looking for a “healthy” leaf.

Thorns grow up to 3 in (7 cm) long.

Needlelike hairs can inject a painful mix of chemicals. The gummy white sap of this flowering plant is toxic to many plant-eating mammals.

The stiff spines that cover the plant can be up to 2½ in (6.5 cm) long. Leaf spots resemble yellow butterfly eggs.

Ants live inside these swollen thorns, protecting the plant from herbivores.

Small birds nest in spiky

gorse bushes to protect themselves from predators.

Stems and leaves are covered in tiny stinging hairs. Buds contain yellow flowers with a coconut scent.

Downward- pointing prickles grow on the stems of roses to deter predators from climbing up.