SPECIES OF CASSIA WHICH YIELD SENNA. 
267 
treated of them ; the suggestions thrown out with the view of 
solving some of the doubts originating from conflicting re- 
cords, and the mode of reasoning, founded on some of the 
circumstances which regulate the changes of plants, are not 
intended to usurp the place of facts. These must speak for 
themselves, wherever they can be positively ascertained; but 
in the present instance, it is the want of them, which we have 
to lament. The subject is still capable of much elucidation, 
and it is to be desired that the obscure portions of the history 
of the Sennas, may soon be satisfactorily determined. 
The most conspicuous plant which enters as an adulterating 
article is the Argel; it belongs to the genus Cynanchum; it is 
called C. argel,hy Delile, and C. oleaefolium,hy Nectoux; 
prior to the investigations of these botanists it was unknown. 
Cynanchum is placed by Lindley, in the natural Order 
Asclepiadeae; it formerly was ranged in that of Apocynae of 
Jussieu; and Delile describes it as appertaining to this order. 
Between Apocyneae and Asclepiadeae, a distinction has been 
drawn by Mr. R. Brown, founded upon the peculiar charac- 
ter of the reproductive apparatus. In the first mentioned, all 
the interior parts of the flower within the corolla are distinct; 
" but in the latter, all of them are consolidated into a single 
body, the centre of which is occupied by a broad disklike 
stigma; and the grains of pollen cohere, in the shape of 
waxy bodies, attached finally to the five corners of this stig- 
ma, to which they adhere by the intervention of peculiar 
glands." 
Cynanchum presents these peculiarities, as may be observed 
from its generic description. Calyx 5-toothed, very small 
and persistent. Corolla rotate. Lepanthium simple, cylindric, 
five to twenty lobed, surrounding the orifice of the tube. Sta- 
minaasin Asclepias. Stigmatatwo. Follicles two. Seedcomose. 
The species which now interests us is thus characterized: 
C. argel, caule bipedali, erecto ramoso, foliis lanceolatis gla- 
bris. 
The stem, which is about three feet high, sends off slender, 
straight, cylindrical branches; the leaves are opposite, lanceo- 
late, of a pale green hue, supported on short petioles, their 
