Morphological and histochemical investigation on glandular trichomes of Orobanche ramosa subsp. nana (Orobanchaceae)

Glandular trichomes present in the stems and flower parts of Orobanche ramosa L. subsp. nana (Reuter) Coutinho were examined under conventional microscopy, UV microscopy and scanning electron microscopy. The ontogenesis and morphology of the glandular trichomes appeared to be identical to those reported for other species belonging to Geraniaceae, Solanaceae, Cannabaceae and Scrophulariaceae. Histochemical investigations were performed to qualitatively detect the main classes of compounds occurring in the glandular hairs and in the secretion. The results achieved suggested the presence of terpenes and flavonoids as the main chemicals. The absence of positive reactions to sesquiterpenes contrasts with similar previously written papers which report sesquiterpenes, together with phenylpropanoids and iridoid glycosides as characteristic chemicals of the genus.