"At very high temperatures, eucalypt species release a flammable gas that mixes with air to send fireballs exploding out in front of the fire. With eucalyptus, you see these ember attacks, with huge bursts of sparks shooting out of the forests, Bowman says. “It’s just an extraordinary idea for a plant.”
Though it’s difficult to prove, Bowman suspects the trees evolved to be “uber flammable.” Sixty million years ago eucalyptus species hit on a way to recover from intense fire, he explains, using specialized structures hidden deep within their bark that allow rapid recovery through new branches, instead of re-sprouting from the roots like other trees. “They have this adaptive advantage of not having to rebuild their trunk. Whether their oil-rich foliage is also an adaptation, we don’t know.”
If you aren’t familiar with the idea of a plant designed to burn in its life cycle, you can get fooled by its beauty and nice smell, Bowman says. “But on a really hot day, those things are going to burn like torches and shower our suburbs with sparks. And on an extremely hot day, they’re going to shoot out gas balls.”
With tiny pinhead seeds that germinate only in disturbed soils, the trees really aren’t good invaders, Bowman says–with one exception. “Fire opens up the woody capsules that hold the seeds, which love growing on freshly burned soil. Give a hillside a really good torching and the eucalyptus will absolutely dominate. They’ll grow intensively in the first few years of life and outcompete everything.”
Eucalyptus are not indigenous to California.They did not appear until the 1850's
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