Anatomy and composition of the essential oil of Larix decidua L. (Pinaceae)

Abstract

Larix decidua L. is a deciduous coniferous native to the mountains of central Europe, in the Alps and Carpathians. The aim was to investigate anatomy and the chemical composition of the essential oils of needles, stems and strobilus of L. decidua. The samples were collected from larch trees from cultivated conditions (Belgrade, Serbia.) and from natural habitat (Alps, Austria). Needles of L. decidua, on cross section are more or less elliptically shaped. Two small secretory canals are in the mesophyll of the needles, on their lateral sides, just below the epidermis. The young stem (primary structures) have canals in cortex, some are just below the epidermis and many, that are in forming phase above the phloem. The older stem (perennial stem) has many secretory canals in the parenchyma of cortex and in the xylem of secondary wood. The essential oils were obtained by hydrodistillation and qualitative and quantitative analysis was performed by GC-FID and GC-MS. Small amounts of essential oils were extracted from the needles (0.06-0.41%), stems (0.31-0.54%) and strobilus (0.16 % and 0.19 %) of L. decidua. The monoterpene (28.70-50.40%) and sesquiterpene compounds (41.80-67.20%) dominated in the essential oil of needles, monoterpenes (80.50-91.70%) in the oil of stems, diterpenes (46.50% and 40.50%) and monoterpenes (24.20% and 22.20%) in the oil of strobilus. Main com- pounds in the essential oil of needles represented germacrene D (15.2-46.9%), δ-3-carene (4.6-24.6%) and α-pinene (6.3- 14.1%), in the oil of stems α-pinene (12.8-21.8%), δ-3-carene (8.6-14.3%) and sabinene (0.5-10.3%), while in the oil of strobilus diterpene of abietane type (4.1-10.2%) and nor-abietatetraene (3.9-9.2%) were the most abundant. The larch needles and stem essential oils from cultivated and natural habitats were quite similar in qualitative composition. However, the essential oil of needles from natural habitat contained higher content of germacrene D and α-pinene and the oil of stem α-pinene and trans-verbenol. The oil of larch strobilus from natural habitat was characterized by manool and 3-α-acetoxy-manool, diterpenes that were not present in the oil of cultivated sample.