The essential oil from Haplophyllum tuberculatum organs were analyzed by Gas Chromatography (GC) and Gas Chromatography–Mass Spectroscopy (GC–MS). The variation of the oils composition attributed to organs was studied. Oils exhibited large phytotoxic effect on the investigated species Triticum aestivum L. and Raphanus sativus L. The hydrosols of leaves, stems and leaves + stems inhibited seeds germination at higher concentration. The volatile oils and hydrosols were found to possess an allelopathic activities.