Résumé
ABSTRACT Hyptis carpinifolia Benth., Lamiaceae, is a species known popularly as "rosmaninho" and "mata-pasto", and leaves are employed in Brazilian folk medicine to treat colds, flu, and rheumatism. The aim of this study was to perform a morphological description of H. carpinifolia and to evaluate the seasonal chemical variability of the leaf essential oils during 12 months. Macroscopic characterization of H. carpinifolia was carried out with the naked eye and with a stereoscopic microscope. Essential oils were isolated from leaves by hydrodistillation in Clevenger apparatus and analyzed by gas chromatography/mass spectrometry. Major compounds were found to be 1,8-cineole (39.6-61.8%), trans-cadina-1(6),4-diene (2.8-17.5%), β-caryophyllene (4.4-10.0%), prenopsan-8-ol (4.2-9.6%) and β-pinene (2.9-5.3%). Results of essential oils compositions were processed by cluster analysis and principal component analysis. Data showed high variability in the concentration of the components. Besides, there was a seasonal variability of chemical composition, probably related mainly to the rainfall regime.