Grasstrees growing next to busy highways are flowering more often because they are breathing in car exhaust.
Many plants only bloom after a major disturbance like a forest fire clears the area. Vehicle exhaust contains a gas called ethylene which is a powerful plant hormone. These trees mistake the constant stream of pollution for the smoke of a natural fire. This accidental signaling forces the plants to bloom out of season and expend energy at the wrong times. This discovery shows how human infrastructure can fundamentally disrupt the life cycles of native species without even touching them.
Heavy road traffic promotes flowering of the grasstree, Xanthorrhoea preissii – a preliminary investigation
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Abstract Grasstrees are renowned for their ability to flower after fire. They are a popular species for ornamental landscaping and anecdotal observations indicate much higher levels of flowering of Xanthorrhoea preissii than occur among unburnt plants in nature. Also, unburnt grasstrees in nature reserves beside major roadways in Perth, Australia, appear to flower much more frequently than those some distance from the roadway. We chose a reserve site 6 km south of Perth with prolific flowering o