172 SCIENTIFIC AND APPLIED PHARMACOGNOSY 



Cannabinese. The Urticacese have a number of distinctive ana- 

 tomical features. Cystoliths or cystolith-like structures are very 

 general; the cell walls are not infrequently silicified or calcified; the 

 bast fibers are of considerable length; calcium oxalate occurs in the 

 form of rosette aggregates or solitary crystals; and both glandular 

 and non-glandular hairs may be present. 



ULMACE.E, OR ELM FAMILY 



They consist mostly of shrubs and trees growing in the tropics 

 and in temperate regions. In addition to the general anatomical 

 features already mentioned, under the Urticaceae, many of the plants 

 of this family have distinct mucilage cells, as in Ulmus, in which 

 they are very prominent. In the latter they are in the form of short 

 cylindrical cells and very regularly arranged in the bark, giving 

 the transverse section a checkered appearance. 



ULMUS. Slippery-Elm Bark. The bark of Ulmus fulva (Fam. 

 Ulmaceae), a tree indigenous to the eastern and central United 

 States and Canada. The bark is collected in spring, deprived of the 

 periderm and dried, the commercial article coming chiefly from 

 Michigan. 



Description. In flat oblong pieces about 30 cm. long, 10 to 15 cm. 

 in diameter, 3 to 4 mm. thick; outer surface light brown, longitu- 

 dinally wrinkled and furrowed and with occasional dark-brown 

 patches of periderm; inner surface yellowish or light brown, more or 

 less uniformly wrinkled longitudinally; fracture fibrous, surface 

 light brown, porous from large mucilage cells; odor slight, distinct; 

 taste mucilaginous. 



Inner Structure. Bast fibers in small groups forming an inter- 

 rupted circle separated by the 4- to 6-celled medullary rays; leptome 

 in alternating interrupted circles, each band or plate having a large 

 mucilage cell. Parenchyma (occasionally reticulately thickened), 

 and cells of the medullary rays frequently contain very small starch 

 grains. The bast fibers are usually surrounded by a nearly closed 

 ring of crystal fibers, each of the cells containing a monoclinic prism 

 of calcium oxalate. 



Powder. Very light brown; bast fibers numerous, very long, 

 about 0.020 mm. in diameter, with rather thin, slightly lignified 

 walls; calcium oxalate in monclinic prisms, mostly in crystal-fibers, 

 the individual crystals from 0.010 to 0.025 mm. in diameter; frag- 

 ments of large mucilage cells with adhering starch grains; the latter 



