82 



ESSENTIALS OF VEGETABLE PHARMACOGNOSY. 



chomes (Indumentum) which they bear; 

 second, as to the general surface effects 

 which result from the latter. The former 

 method, while not admissible in this ar- 

 ticle, is of very great importance in the 

 characterization of medicinal herbs and 



less elongated, it is called Tomentellate. 

 When there is a covering of thinly dis- 

 tributed, elongated, moderately soft 

 hairs, which are not closely appressed, 

 the surface is Pilose. When hairs are 

 similarly distributed, hut are elongated 



f'g. 3^2. 



leaves, especially as it constitutes one of and coarse, the surface is Hirsute. When 

 the greatest aids to the identification of similar coarse hairs are rather stiff, lie 

 powders. The latter method can only be 



studied with advantage by the actual ex- 

 amination of type specimens, it being al- 

 most impossible to characterize the dif- 

 ferent forms by definition. A surface is 

 Opaque when it is not shining or lustrous. 

 It is Glabrous when it does not possess 

 any trichomes in such forms as to detract 

 from a smooth surface. It is Glaucous 

 when covered with a waxy exudation, 

 imparting to it a peculiar whitish appear- 

 ance ("bloom"), such as characterizes the 

 surface of an ordinary black grape. It is 

 Scurfy when covered with more or less of 

 an appendage in the form of granular or 

 detached scaly masses. When the matter 

 of such masses is more thinly distributed, 

 appearing in the form of a powder rather 

 than a scurf, the surface is called Pul- 

 verulent. A Pubescent surface is a hairy 

 surface, which is not readily distin- 

 guished as pertaining to any one of the 

 other specific classes. If the hairs of a 

 pubescent surface are very short and fine, 

 so that the consequent roughness is re- 

 duced to a minimum, the surface is called 

 Puberulent. If a hairy indumentum is 

 fine and of an ashy gray color, the hairs 

 not arranged in any regular direction, the 

 surface is Cinereous. If the hairs all lie 

 in one direction, are closely appressed and 

 have a shining or silky lustre, the surface 

 is called Sericeous. If this lustre is in- 

 tensified and of a strongly whitish color, 

 whether the trichomes be hairs or scales, 

 the surface is denominated Argenteous, 

 Such hairs as are capable of producing a 

 sericeous surface are themselves denomi- 

 nated sericeous or silky, even though 

 they be in insufficient numbers to impart 

 this character to the general surface. A 

 surface tending toward the sericeous, but 

 not sufficiently pronounced, is called Can- 

 escent. When there is a dense covering 

 of more or less elongated and matted 

 hairs, the surface is called Tomentose. 

 When such a coyenng is thin, its hairs yielding and sharp pointed, the surface is 





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in one direction, somewhat appress nl, 

 and particularly when each develops from 

 an elevated base, the surface is Strigose. 

 A surface which possesses an indumen- 

 tum of scales is called Lepidote. When 

 the indumentum consists of hard, ele- 

 vated points, giving a roughness to 'he 

 surface, the latter is Scabrous, When 

 such elevations are more pronounced, un- 



