244 SCIENTIFIC AND APPLIED PHARMACOGNOSY 



made up of distinctive tissues as follows: (1) Alternate rings or zonea 

 composed of wood-wedges having large tracheae, surrounded by 

 wood fibers and separated by broad starch-bearing medullary rays; 

 each wood-wedge also has at the periphery a semicircular strand of 

 leptome. (2) Alternate rings or zones of starch-bearing parenchyma 

 marked upon the inner face by a nearly closed ring of stone cells. 

 Periderm consisting of a number of layers of narrow blackish-brown 

 cork cells and having beneath usually a distinct phellogen layer. 



A distinct pit is absent in the root and only occurs in the stem 

 which otherwise has a structure resembling the root. 



FIG. 110. Photographs of typical specimens 01 true Pareira, the pieces in trans- 

 verse section showing concentric rings of fibrovascular tissue. 



Powder. Dark brown or yellowish-brown starch grains numer- 

 ous, mostly single, occasionally unequally 2- to 4-compound, the 

 individual grains ellipsoidal, spheroidal, or oblong, varying from 

 0.005 to 0.020 mm. in diameter and occasionally with clefts or irreg- 

 ular markings; fragments of long wide trachese, marked mostly 

 with numerous slit-like pores and associated with long thick-walled 

 porous and strongly lignified wood fibers; stone cells in small groups 

 with thick walls and numerous radiating pores; fragments of paren- 

 chyma filled with starch grains, those of the root being thick-walled, 



