Abstract Limited experiential contact to natural environment can affect the knowledge of the local flora and, consequently, the intentions to conserve it. Therefore, this study aims to analyze whether high school students from Teresina (PI-Brazil) can identify more species of native than exotic plants and the factors that can affect this ability. 333 students from state public schools were interviewed through semi-structured questionnaires and with printed images of 20 species of plants found in the region. The data were analyzed using univariate non-parametric statistics. The results show that living in the countryside positively influenced the identification of local flora, but there was no significant difference in the number of identified plants between students who attended botany classes and those who did not. Two native plants (cashew-96.7% and pitomba-91.9%) and three exotic plants (mango-90.7%, guava-94.9% and acerola-82.0%) stood out among the most identified plant species. It was also found that, for two species of native plants very important for the State of Piauí, the caneleiro (0.6%) and the carnauba (26.7%), the identification rates were scarce. Thus, it is necessary to use Environmental Education and the teaching of Botany to prioritize native plant species, valuing local ecology and ensuring their protection.