HYDRANGEA 287 



light brown, bark thin, easily separable from the distinctly radiate 

 wood which surrounds a prominent whitish pith; inodorous; taste 

 of the bark sweetish, becoming slightly acrid. Roots attaining a 

 length of 25 cm. and a thickness of 2 mm., irregularly bent and 

 branching, otherwise resembling the rhizome with the exception of 

 the pith being wanting. 



Inner Structure. A corky layer consisting of several rows of 

 grayish- white tabular cells; cortex consisting chiefly of starch- 

 bearing parenchyma, large cells containing raphides, small isolated 

 groups of stone cells, and sclerenchymatous fibers; a woody cylinder 

 composed of slender wedges made up of prominent tracheae with 

 reticulate thickenings and tracheids, separated by the starch-bearing 

 medullary rays which are from 1 to 3 cells wide; pith of large polyg- 

 onal cells with prominent simple pores. 



Powder. Light yellowish-brown; irregular fragments consisting 

 of strongly lignified tracheae, tracheids and medullary ray cells; 

 stone cells and sclerenchymatous fibers, 0.050 to 0.200 mm. in length, 

 strongly lignified, the walls being marked by simple and branching 

 pores; raphides numerous, from 0.070 to 0.130 mm. in length; 

 starch grains mostly single, more or less ellipsoidal, occasionally with 

 a prominent central cleft, and varying from 0.002 to 0.010 mm. in 

 diameter. 



Constituents. A glucoside, hydrangin, about 1 per cent, crys- 

 tallizing in aggregates, soluble in alcohol and ether, and giving with 

 solutions of the alkalies a bluish fluorescence, which immediately 

 disappears on the addition of acids. Also a volatile oil, resin and 

 starch. It probably also contains a saponin. A glucoside, para- 

 hydrangin, is also present in the root of the arborescent Hydrangea 

 (H. Paniculata grandiflora), a variety extensively cultivated. 



Mostly sub-tropical trees or shrubs and represented by about 

 35 species. The leaves are alternate, the flowers perfect or polyga- 

 mous, usually having an imperfect perianth, and the fruit is a woody 

 capsule, dehiscing at the summit. In the axis the trachese are usually 

 narrow and possess scalariform perforations or have simple pores 

 when in contact with the medullary ray cells. The wood fibers bear 

 simple pores and the medullary rays are but a few cells wide and a 

 great many rows in height. The non-glandular hairs are either stel- 

 late or tufted. Calcium oxalate is excreted either in the form of 



