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Background. Wildfires are a growing threat, especially in Mediterranean climate areas during periods of drought. The wildfire research community continues to investigate propagation mechanisms considering thermal transfer and fluid mechanics and sometimes a simplified chemistry taking into account the main combustion products such as CO, CO 2 , H 2 O, H 2 and CH 4 . However, volatile organic compounds (VOCs) cannot be neglected and have a major role in vegetation ignition. Despite this, knowledge on the influence of wildfire on plant emissions remains lacking. Aims. This work addresses the effect of combined hydric and thermal stresses on the physiology and emissions of Rosmarinus officinalis and Cistus albidus, which are widely consumed in Mediterranean wildfires. Methods. Plants were submitted to hydric stress inside a greenhouse, then to thermal stress inside a heated hermetic enclosure while collecting emissions with adsorbent elements for analysis. Simultaneously, heating experiments were carried out with leaves sampled to analyse their emissions. Key results. The heating tests showed significant variations in monoterpene, fatty acid and alkane emissions between stressed and unstressed plants with different results between Rosmarinus officinalis and Cistus albidus. Conclusion/implication. Further experiments with other plant species and quantification of emissions may help to better know why Mediterranean wildfires are a particular threat and how to improve firefighting methods.

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