412 VALERIANE.E 



pith. Nucleus sheath mostly indistinct; branches have a similar 

 structure but a thicker bark. The rootlets have a thick bark and a 

 slender, woody column, distinctly radiate, and contain a small pith 

 inclosed in a nucleus sheath. 



Powder. Characteristic elements: See Part iv, Chap. I, B. 



FIG. 239. Valerian Cross-section of rhizome. A, Cork cells. B, Collenchyma. C, Cortical 

 parenchyma. D, Endodermis. E, Small irregular liver-cells. F, Medullary rays. G, Punctuated 

 vessels of wood-rays. H, Pith-cells. 



FIG. 240. Valerian Cross-section of rootlet. (17 diam.) A, Epidermis, B, Parenchyma of 

 cortex. C, Phloem. D, Xylem. (Photomicrograph.) 



CONSTITUENTS. Besides the common vegetable principles, it contains a 

 terpene, isovaleric acid, CsHioC^ (distilling at 3ooC.), and a volatile 

 oil of complex constitution, consisting mainly of an alcohol, borneol; 

 its ether, and its formic, acetic, and valerianic acid esters, which are 



