Coloured polarised light micrograph of a Tasmanian blue gum (Eucalyptus globulus) stem. This tree, formerly Eucalyptus gigantea and also known as the Southern blue gum, is an evergreen tree native to Tasmania and Victoria, Australia. It produces hard durable timber. The leaves are the principal source of eucalyptus oil which is an antiseptic used as a decongestant for treating catarrh, bronchitis and influenza. It is also used in liniments for bruises, sprains and muscular pains, and to make herbal tea infusions and strongly flavoured honey. Magnification: x22 at 10 cm wide.