For the first time, chemical composition of P. longifolium essential oils (EO) and head space (HS) volatiles obtained from the fresh leaves, harvested in different phases of the plant development, and inflorescences was compared. The major contributor of leaves essential oil in vegetative phase (LD) was β-elemene (44.1%). On the contrary, β-elemene (22.5%) was the second most abundant component, while (E)-β-ocimene (26.7%) was the first and cis-lanalool oxide (furanoid, 21.9%) was the third most represented compound in the leaves essential oils collected in blossoming phase (LF). (E)-β-Ocimene was the major compound in both HS leaf samples but in very varying amounts (LD 81.8% and LF 27.4%). Beside (E)-β-ocimene, p-cymene and limonene were represented more than 10% (13.6% and 15.2% respectively). The essential oil and HS volatiles of the inflorescences was characterized by a high content of β-phellandrene (16.4% and 20.4% respectively), α-phellandrene (22.5% and 13.9% respectively) and myrcene (23.1% and 22.1% respectively). The presented data showed that there was a significant difference in the composition of volatile components from different plant organs and also from the same organ in different stages of development.