The morphology, distribution and release mechanism of the glandular trichomes of Teucrium salviastrum Schreber were studied, along with the chemical composition of the essential oils. Peltate and capitate trichomes are present on both vegetative and reproductive organs. In this study, particular emphasis is given to the capitate trichomes with long multicellular stalks. These trichomes are very abundant, and the secretion material is released by cuticule rupture on the top of the head cells. Also noteworthy is the presence of peltate trichomes on the upper surface of the ovary. Although already described in some Lamiaceae, these trichomes have not been recorded previously on any other Teucrium species. The composition of the essential oil was studied using mainly GC and GC-MS. The oils isolated from leaves, collected during the flowering and post-flowering phases of the plant, as well as the oil isolated from the flower heads, exhibited a similar chemical composition. Nevertheless, the oils showed remarkable differences in composition when compared to those reported in the literature for the same species. The present study has shown that our oil consisted mainly of E-ˇ-farnesene (26.1-29.3%), E-caryophyllene (19.1-24.1%) and germacrene D (13.7-21.6%). The major compound of our samples, E-ˇ-farnesene, is reported for the first time for this species.

The morphology and distribution of the glandular trichomes of Teucrium capitatum L., as well as the chemical composition of the essential oils, were studied. Important differences were found with regard to the major constituents of the essential oils of five populations of T. capitatum grown in Portugal. The oil isolated from one population was characterized by a high content of oxygenated monoterpenes (33.0%), isomenthone (7.7%) being the major constituent. Another oil from a population collected from the same region was dominated by monoterpene and sesquiterpene hydrocarbons (43.9% and 23.2%, respectively), α α α α α-pinene (7.7%), sabinene (11.2%) and β β β β β-pinene (10.3%) being the main compounds. The oils from the other three populations were characterized by a high content of both sesquiterpene hydrocarbons (23.0%, 32.2% and 33.2%) and oxygenated sesquiterpenes (39.7%, 23.4% and 20.4%). T-cadinol (24.1%) and α α α α α-cadinol (9.8%) were the major compounds in the oil from one population, whereas δ δ δ δ δ-cadinene (7.5% and 9.8%) and E-caryophyllene (5.4%) or α α α α α-muurolol (6.0%) were the major constituents in the other samples. The indumentum of the vegetative and reproductive ograns from the five populations of T. capitatum, observed under scanning electron microscopy, showed the same type and distribution of glandular and non-glandular trichomes. Since the ecological and edaphic features of the collecting sites were quite similar, the chemical polymorphism observed seems to be due to genetic factors.

Recent classifications proved to be more accurate in predicting important clinical outcomes in patients with AP.

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