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PHARMA CO GNOS Y. 
II. ROOTS AND RHIZOMES. 
Roots and rhizomes represent those parts of plants 
which develop under ground, the latter having all of 
the characteristics of stems except in their manner of 
growth. Most drugs derived from roots and rhizomes 
possess the typical characteristics of these plant parts, 
the commercial products being readily distinguish- 
able as such. There are some, however, that are more 
or less intermediate in character, and while commonly 
spoken of as roots, they are in reality modifications 
of the stem, at least in part, as aconite, gelsemium, 
glycyrrhiza and rhubarb. For this reason, and in 
order to facilitate their study, roots and rhizomes are 
here considered in one class, which is subdivided as 
follows : (1) True Roots ; (2) Rhizomes that are root- 
like, at least in part ; (3) True Rhizomes ; (4) Conns ; 
(5) Bulbs. 
Some of the roots and rhizomes that are employed 
in medicine are prepared for market by removing a 
part of the periderm ; in a general way this treat- 
ment is objectionable, particularly in the case of those 
drugs containing volatile principles, as these exist in 
greatest amount in the cortical portion, and the peri- 
derm serves to prevent the volatilization as well as 
deterioration of these principles. 
Rhizomes are distinguished as upright, horizontal or 
oblique, depending upon their manner of growth, and 
this may be determined in the drug by placing the 
rhizome in such a position that the stem-scars are 
horizontal. 
I. Roots. 
1. Monocotyledons ■ Sarsaparilla 
2. Dicotyledons. 
A. Periderm removed Althaea 
B. Periderm present. 
