SERPENTARIA 187 



with stem-scars or stem-remnants, under and side portions with 

 numerous roots and root-scars; fracture short; internally, bark 

 dark brown, 0.3 to 0.5 mm. in thickness, wood yellow, radiate, por- 

 ous, 1 to 1.5 mm. in thickness, pith 1 mm. in diameter; odor tere- 

 binthinate; taste bitter, aromatic. 



Roots nearly straight, 4 to 7 cm. in length, about 0.3 mm. in 

 diameter, longitudinally wrinkled, bark light brown, wood yellowish, 

 5-rayed. 



Texas Snakeroot. Rhizome 10 to 40 mm. in length, 1 to 3 mm. 

 in diameter; roots about 0.5 mm. in diameter, with numerous more 

 or less interlacing rootlets. 



Inner Structure. (Fig. 79.) Rhizome with an outer corky layer; 

 bast fibers either single or in groups and forming a more or less closed 

 ring; xylem composed of tracheae and wood fibers forming broad 

 wedges; medullary rays about 8 cells wide the walls being porous 

 and strongly lignified. Numerous starch grains occur in the paren- 

 chyma cells of the cortex and pith and in the medullary rays. The 

 root in section shows a compact 4- to 6-rayed stele and a wide starch- 

 bearing cortex. The stem is distinguished by a continuous ring of 

 schlerenchymatous fibers, and a few typical non-glandular hairs, 

 the terminal cells being somewhat recurved in the form of a hook. 



Powder. Grayish-brown or dark yellow ; starch grains numerous, 

 single and 2- to 4-compound, the individual grains, from 0.003 to 

 0.014 mm. in diameter, being more or less spheroidal or plano-convex, 

 and frequently with a central cleft; lignified elements numerous, 

 consisting of tracheae, wood-fibers, medullary ray cells and pith 

 cells; a few typical non-glandular hairs of the stem are occasionally 

 present. 



Constituents. Volatile oil 0.5 to 1 per cent, the important con- 

 stituent of which is borneol; a bitter poisonous principle, aristol 

 lochin (serpentarin), an alkaloidal principle, aristolochine; several 

 organic acids; starch; ash about 10 per cent. 



Substitutes. The rhizome of yellow root (Jeffersonia diphylla) 

 is sometimes substituted for serpentaria, from which it is distin- 

 guished by its lack of odor and by having a bitter, acrid taste. 



POLYGONACE^E, OR BUCKWHEAT FAMILY 



Mostly herbaceous plants, with nearly entire leaves, and dis- 

 tinguished by having jointed stems, usually sheathing united stipules 

 and a 3- to 4-angled achene. The plants also usually contain tannin 

 cells and' resinous secretory cells, the latter sometimes being branched 



