112 



PLANT ORGANS OR PARTS OF PLANTS. 



yellowish powder, smooth or slightly wrinkled, marked 

 with white, elongated meshes, containing a spongy tissue 

 and a number of short, reddish-brown striae; compact, 

 hard, fracture uneven, internally white with numerous red, 



Fig. 22. — Rhubarb. 

 Cross-section of root portion: c, Cambium surrounding a central 

 phloem with medullary rays, m, and numerous crystals, obliterated 

 sieve tubes and parenchymatic cells; g, vessels; ph, parenchyma in 

 phloem. Starch is found in many of the cells. 



irregularly curved, and interrupted rays which are radially 

 parellel only near the cambium line; odor aromatic, taste 

 bitter and astringent. 



Histology. — When examined with the lupe, large 

 or small remnants of the dark outer cortex are seen. 



