Thorn trees are plants that have sharp, pointed structures called thorns, which serve as a defense mechanism against herbivores. These trees are commonly found in arid and semi-arid regions, where they have adapted to survive harsh conditions. Examples of thorn trees include the Acacia and Hawthorn, which can thrive in poor soil and require minimal water. The thorns of these trees can vary in size and shape, providing protection from animals that might eat their leaves or bark. Additionally, thorn trees often play a crucial role in their ecosystems, offering shelter and food for various species, including birds and insects.