288 SCIENTIFIC AND APPLIED PHARMACOGNOSY 



solitary crystals or rosette aggregates. Tannin secretion cells are 

 very characteristic in Hamamelis. Schizogenous resin canals occur 

 in Liquidambar. They occur commonly at the margin of the pith 

 and can be traced into the finest branches of the veins of the leaves. 

 In roots they are associated with the development of primary and 

 secondary phloem. 



HAMAMELIDIS FOLIA. Witchhazel Leaves. The leaves of 

 Hamamelis virginiana (Fam. Hamamelidaceae), a shrub indigenous 

 to the eastern and middle United States and Canada. The leaves 

 are collected in autumn, and are used in the fresh condition, or dried ; 

 when dried they should be carefully preserved and not kept longer 

 than one year. 



Description. Broadly elliptical, or rhomboid-obovate, more or 

 less unequal; 3.5 to 12 cm. in length, 2.5 to 7 cm. in breadth; summit 

 rounded, acute or acuminate; base obliquely cordate; margin 

 sinuate or sinuate-dentate; upper surface dark green, veins of the 

 first order diverging at an angle of about 60 and running nearly 

 parallel to the margin, with grayish patches of a mold and slightly 

 pubescent; under surface light green, pubescent, midrib and veins 

 prominent; petiole 5 to 12 mm. in length; texture coarse, brittle; 

 odor slight; taste astringent. 



Inner Structure. (Fig. 129.) Epidermal layer of the ventral 

 surface, glabrous except above the midrib and the large secondary 

 veins; stomata are only found upon the lower surface, these being 

 narrow elliptical, about 0.015 mm. in length with 2 to 4 neighboring 

 cells; from both surfaces, but especially from the under surface, 

 arise stellate hairs composed of from 4 to 12 cells united at the base, 

 the individual cells being from 0.030 to 0.075 mm. in length, either 

 straight or more or less bent and with very thick walls and narrow 

 lumina, sometimes only apparent in the lower portion of the cells; 

 a palisade layer consisting of a single row of cells and a dorsal pneu- 

 matic tissue made up of from 3 to 6 rows of strongly branching cells; 

 the fibrovascular bundles occurring in the midrib and petiole are large 

 and of the collateral type, with a central area composed of paren- 

 chyma, surrounded by a strongly developed xylem, the tracheae 

 being narrow, mostly spiral and associated with numerous narrow, 

 strongly lignified wood fibers, the pores being prominent ; the phloem 

 consists of leptome surrounded by a nearly continuous circle of bast 

 fibers, the walls of which are strongly lignified; calcium oxalate 

 occurs in monoclinic prisms from 0.010 to 0.035 mm. in diameter, 

 occurring either in the cells of the mesophyll or in crystal fibers, the 

 latter associated with the bast fibers. 



