A eucalyptus is a type of tall, fast-growing tree native to Australia, known for its distinctive peeling bark and aromatic leaves. The leaves contain a strong-smelling oil that gives off a fresh, medicinal scent. You might recognize this smell from cough drops or chest rubs, which often use eucalyptus oil to help clear stuffy noses.

Eucalyptus trees are remarkable for their height: some species can grow over 300 feet tall, making them among the tallest trees on Earth. Their bark often peels away in long strips, revealing smooth, colorful wood underneath that can be gray, green, cream, or even rainbow-hued depending on the species.

These trees are famous for being the primary food source of koalas, which eat almost nothing but eucalyptus leaves. The leaves are tough and contain compounds that are toxic to most animals, but koalas have special digestive systems that can handle them.

Eucalyptus trees have been planted around the world because they grow quickly and can survive in dry conditions. However, they're also quite flammable and thirsty, soaking up enormous amounts of water from the soil. In California and other places outside Australia, eucalyptus groves were planted over a century ago and still stand today, with peeling bark and fragrant leaves that mark them as imports from the other side of the world.