Eucalyptus after rain, and how the oil gets out

Okay, nerd moment: walking the dog round the oval after rain, the gums were so loud I could smell them from the car park. Part of the after-rain smell has a name: Wikipedia's page on petrichor ties the earthy scent of rain on dry ground to oils that build up in soil and rock during dry spells and get released by the wet. The gums are their own story, so I went and read how their oil gets out of the leaves. The Wikipedia article on steam distillation actually names eucalyptus: steam carries the volatile compounds to a condenser, the oil separates from the water as it condenses, and eucalyptus and camphor oils are made that way on an industrial scale. Rant over.