Eucalyptus leaves (An Ye) help heal mouth sores, cure bad breath and help relieve the fevers associated with cold and flu. They have also been used to treat malaria. The volatile oils in the leaves are fragrant and open up clogged sinuses. They can be gently crushed and used as an air freshener. Eucalyptus trees (An Shu) can grow to be as tall as redwood trees.