Eucalyptus is a very unique looking tree. It has leathery leaves which hang downwards and a tall, straight trunk which is mostly white in colour. It is a very fast growing tree which can sometimes grows 4 metres in a year. Some eucalyptus trees grow as tall as 140 metres. These trees are very useful for humans. They are often planted in marshy areas to fight malaria, as they soak up the water in mosquito-infested swamps. The essential oil extracted from eucalyptus is used as medicine to clear nasal passage and combat congestion and asthma. The oils also help cure ailments related to kidney and nervous system. Eucalyptus wood is used as construction material too.