GENTIAN 



345 



separating a rather thick bark from a large central portion (wood) in 

 which vascular tissue can with difficulty be discerned, as, like the 

 bark, it consists almost entirely of parenchyma ; neither bark nor 

 wood exhibits any radiate structure. 



The rhizome is easily distinguished from the root by the absence 

 of conspicuous longitudinal wrinkles, and the presence of close, 



FIG. 179. Gentian root. A, root, showing surface with longi- 

 tudinal wrinkles. B, rhizome, showing fine transverse lines 

 (leaf scars), and dividing into two branches, each terminating 

 in a bud. Natural size. 



transverse annulations. It often exceeds the root in diameter, and 

 may attain a length of 30 cm. or more. Each transverse annulation 

 represents a year's growth, and bears the scars of fallen leaves, the 

 minute fibro- vascular bundles of which are evident under a lens. 

 The rhizome, which occasionally branches, is usually crowned with 

 a large bud protected by dry, scaly leaves. 



Roots that have been longitudinally sliced before they were dried 

 frequently exhibit transverse instead of longitudinal wrinkles, and 

 are paler internally ; otherwise they correspond to the description 

 given. 



