Histochemical localization of secretion and composition of the essential oil in Melittis melissophyllum L. subsp melissophyllum from Central Italy

The distribution and morphology of the secretory structures in Melittis melissophyllum L. subsp. melissophyllum (Lamiaceae) were studied for the first time by light and scanning electron microscopy. The indumentum of the vegetative and reproductive organs includes non-glandular hairs and peltate (type A) and capitate (types B and C) glandular trichomes. Histochemical techniques enabled specific location of the site of essential oil accumulation in the type A peltate hairs. In order to confirm the occurrence of the 1-octen-3-ol chemotype in central Italy, six populations growing in different places were analysed for the essential oil composition by GC-FID and GC-MS. In all populations, 1-octen-3-ol was detected as the major volatile component, representing 56.3-70.6% of the total oils. To date, these percentages are the highest detected in a plant essential oil. Copyright (C) 2009 John Wiley & Sons, Ltd.