394 SUBTERRANEAN ORGANS 



surface with large triangular leaf-scars that encircle the rhizome, 

 springing from each side alternately. To these scars the fibrous 

 leaf-traces are sometimes attached. The under surface bears an 

 irregular zigzag line of small raised root-scars that are circular and 

 exhibit a central stele surrounded by a narrow cortex. The rhizome 

 produces an occasional slender lateral branch which is distinctly 

 marked with the scars of leaves and roots. 



The scraped rhizome is of a pale brownish buff colour, has a 

 roughish surface, and bears less conspicuous scars of leaves and roots. 



The drug breaks with a short corky fracture, and is pale brown, 

 or nearly white, and spongy internally. The section exhibits a large 

 stele separated by a yellowish line from a thick cortex of similar 





FIG. 213. Sweet Flag rhizome. Transverse section, 

 magnified 3 diam. a, cortex ; v, endodermis 

 b, stele ; y, vascular bundles. (Berg.) 



appearance. Both stele and cortex are traversed by numerous small, 

 oval, scattered, fibre-vascular bundles. 



The freshly fractured surface has an agreeable aromatic odour. 

 The taste is disagreeably bitter and pungent. 



The student should observe 



(a) The large triangular leaf -scars, 



(b) The zigzag line of root-scars, 



(c) The spongy texture, 



(d) The bitter, pungent taste. 



Constituents. Sweet flag rhizome contains from 1*5 to 3-5 per 

 cent, of an aromatic volatile oil, the chief aromatic constituent of 

 which is asaryl aldehyde. It contains also an amorphous bitter 

 principle, acorin, yielding by oxidation acoretin and by treatment 

 with acids or alkalies volatile oil and sugar. Certain alkaloidal 

 substances (choline, trimethylamine) appear also to be present, but 



