Folivores are animals that specifically eat the leaves of a plant. Whilst herbivores also eat plants, folivores stay away from the stem or roots. Examples of folivores include pandas, sloths, and koalas.

Plants are living organisms that use leaves to get their energy from the sun. They need their leaves to survive, so have evolved to make them difficult for animals to eat. Often, leaves are full of toxins, are bitter to taste, difficult to chew, and made of large cellulose molecules that are hard to break down in the animals' digestive systems. Due to these defence mechanisms, folivore animals have specialized traits to cope with digestion.

Folivorous mammals have broad teeth that help to physically break down leaves when chewing. Some folivores have stomachs with multiple compartments to help break down the cellulose molecules, and all leaf eaters have long intestines and strong gut bacteria. Folivores tend to be the largest mammals, for instance, elephants, and spend a considerable portion of the day digesting their food. They are often fairly inactive creatures, particularly sloths.

More Info: en.wikipedia.org