Oak leaves are the foliage of oak trees, which belong to the genus Quercus. These leaves are typically lobed, with deep indentations that give them a distinctive shape. They can vary in size and color, often appearing green in spring and summer, and turning shades of red, orange, or brown in the fall. The structure of oak leaves includes a central vein with smaller veins branching out, providing strength and support. Oak trees are found in many regions around the world, and their leaves play a crucial role in photosynthesis, helping the tree produce energy from sunlight.