140 SCIENTIFIC AND APPLIED PHARMACOGNOSY 



bundles each surrounded by an endodermis so that no ring of endo- 

 dermal tissue is present as is characteristic for the monocotyledons; 

 inodorous and very mucilaginous. 



Inner Structure. (Fig. 62). An epidermal layer, when present, 

 of tabular cells, with suberized walls and sometimes developed into 

 long root hairs. The drug consists for the most part of parenchyma 

 either filled with a pasty mass of altered starch grains, or with 

 mucilage cells each containing a bundle of raphides of calcium oxa- 

 late. The fibrovascular bundles are of the radial type each being 

 surrounded by a thin-walled endodermis. 



. Powder. Yellowish-brown, consisting of the tissues above men- 

 tioned. 



Constituents. Mucilage, 48 per cent; starch, 25 per cent; 

 nitrogenous substances, 5 per cent; sugar 1 per cent; ash, from 1.5 

 to 4 per cent; and a trace of volatile oil. 



Adulterants. The flattened, 2- to 5-branched tubers, known as 

 Radix Palmse Christi, do not contain as much mucilage and are 

 sometimes seen in the drug of commerce. The Royal Salep of 

 Afghanistan is edible and is derived from Allium Macleanii. 



DICOTYLEDONS 



The plants of this group are the highest in the plant kingdom and 

 comprise from two-thirds to three-fourths of the living Angiosperms. 

 They are characterized by having two seed-leaves. These leaves 

 also known as primordial leaves are distinguished from those formed 

 later on the stem known as foliage leaves. The latter are usually 

 reticulately veined, i.e., the veinings forming a network. The flower- 

 parts are arranged in spirals of 2 to 5, and are usually readily distin- 

 guished from those of the monocotyledons. The roots and stems are 

 characterized by a distinct wood and bark being formed by a cambium 

 and hence the class is sometimes known as Exogens. The studies 

 on this group of plants have been very extensive and their comparative 

 anatomy is included in an excellent work on " Systematic Anatomy 

 of the Dicotyledons " by Hans Solereder, an English translation of 

 which is available. The general outer morphology of the orders 

 comprising this group are enumerated in Kraemer's Applied and 

 Economic Botany and hence special attention will be given here to 

 generalizations concerning their inner morphology. While, of course, 

 there are some difficulties in framing hard and fast rules, yet the 

 considerations here given will be found very helpful in practice when 

 identifying unknown drugs. 



