Sweet Flag Stem (Acorus calamus). Light micrograph of a section through a fig tree stem. The large holes are cross-sections of xylem, vascular tissue used to transport water and minerals from the roots. The rootstock of this aromatic plant are used as a natural insecticide and an ingredient of perfumes. The roots were used for various medicinal purposes, and reportedly induce hallucinations if eaten in sufficiently large quantities. In modern times the active chemical in the plant has been identified as Beta-asarone, a carcinogen. The Food and Drug Administration (FDA) has banned the use of the sweet flag as a food additive. The magnification is 25 times when printed 10 inches wide.