ii6 



PLANT ORGANS OR PARTS OF PLANTS. 



The odor is slight, tobacco-Hke, increased by moisten- 

 ing. Taste very bitter. 



Histology. — Microscopically a cross-section of gentian 

 root shows an epidermis of thin- walled cork cells, four to 



Fig. 24. — Gentian. 

 Cross-section of cambial portion of root of Gentian, c, Cambium; 

 s, sieve tubes; g, vessels with a few fibres, s, on the inside of cambium 

 (Tschirch) . 



eight rows deep, enveloping a narrow zone of weak col- 

 lenchyma merging into the layer of parenchyma, next 

 within whose loosely arranged tissue are seen occasional 

 sieve bundles but no bast fibres. The dark brown cam- 



