Gasoline also called gas or petrol, mixture of volatile, flammable liquid hydrocarbons derived from petroleum and used as fuel for internal-combustion engines. It’s also used as a solvent for oils and fats. Fossil fuels are still the most source of energy representing approximately 80% of the entire world supply. However, its exploration, recovery and use present serious environmental problems, which are mainly related to the assembly of greenhouse gases and contamination of land and water resources. Phytoremediation is an alternate to costlier remediation technologies because it's a feasible, effective and non-intrusive technology that utilizes natural plant processes to reinforce degradation and removal of contaminants from the environment. Phytotoxicity studies with petroleum on native Brazilian trees included plant growth, root length, produced biomass, tissue analysis, etc. Typical phytotoxicity studies with trees for phytoremediation application also include elaborated research on uptake potential, metabolic pathways, in vitro systems with cell suspension, crown gall cultures, etc. The effect of diesel fuel on plant transpiration during the free phase experiment is represented by the normalized relative transpiration. S. parahyba showed decreased transpiration within the presence of diesel altogether doses tested. Transpiration was reduced by 53%, 42%, 59% and 26% at 8, 16, 33 and 66 gL-1, respectively. The consequences were more severe for M. scabrella and E. contortisiliquum, with a maximum reduction of 76% and 82%, at 16 and 66 gL-1, respectively. It had been observed that the toxic reaction represented by low transpiration rates started at 48 h for M. scabrella and E. contortisiliquum, and later for S. parahyba. Transpiration rates were variable for S. parahyba, as observed by the tiny percentage increase after 72 h of exposure to diesel. M. scabrella showed endless decrease in transpiration throughout the entire experiment.