The anatomy of the vegetative organs of S. orientalis in primary structure was described, emphasizing the characterization and histochemistry of its secretory structures. Leaves, stems and roots were fixed in FAA50 and ferrous sulphate and stored in 70% ethanol. Cross and longitudinal sections were submitted to toluidine blue pH 4.0, ruthenium red, PAS reaction, Ponceau Xylidine reactive, Sudan Black B and Dragendorff reactive. Anatomically, S. orientalis vegetative organs are similar to the characters described for the Asteraceae. The lateral roots are triarches and the stem is an eustele. Ducts are absent in the root and present in the stem and leaf. These structures are of low diameter, being delimited by 4 to 5 epithelial cells. In the stems, the ducts were present in the cortex, next to the endoderm and in the pith. In the leaves, they were associated to the vascular bundles, facing both the xylem and the phloem. The leaves are dorsiventral and amphistomatic. Three types of secretory structures were observed: ducts, hydathodes and glandular trichomes. The histochemical tests showed the presence of phenolic and alkaloid compounds in the ducts, while lipid and phenolic compounds were found in the trichomes. Such results indicate the complex secretion produced by the structures in this species.
weed; medicinal plant; hythiem; shrimp-claw plant; Heliantheae
