268 
ORIGINAL COMMUNICATIONS. 
central nerve is prominent; the flowers are white, numerous, 
and disposed in dichotomous clusters in the axils of the leaves, 
at the summit of the branches; the calyx of each flower is 
short, with five divisions; corolla deeply 5-parted, rotate, 
segments linear and acute; an interior crown, with 5 plicae 
and 5 teeth, surrounds the stamens, which, to the number of 
five, are united in the centre of the flower, so as to form a 
truncated body elevated upon a pedicel formed by the fila- 
ments. The fruit consists of two ovoid pointed follicles, the 
exterior substance of which is glabrous, hard, thick, and spot- 
ted; they contain imbricate, ovoid, comatose seed.* 
At the time Delile wrote, the separation of the order 
Apocynae had not been made; he therefore was correct in as- 
signing to this plant the affinities of this order. Argel is easily 
detected in Senna, by its want of agreement with the charac- 
teristics of Cassia. 
Periploca grxca is also stated to be introduced into Senna. 
Its leaves are not a little unlike the Indian article, except that 
they are destitute of the marked unequal base of the species 
of Cassia, and have a more brilliant green colour. It belongs 
as the above to the family Asclepiadese. 
The Colutea arborescens, which is said to form sometimes a 
part of this drug — belongs to the same order Leguminosae; its 
leaves are small, rounded and strikingly emarginate, with the 
base equal, so that no difficulty is presented in detecting it. 
Indian Senna. — With respect to the plant which furnishes 
this commercial variety of the drug, considerable doubt and un- 
certainty still exist, as may be perceived from the accounts 
which have been given of it. This appears the more extraor- 
dinary, as it has been so long known as a medicine and so much 
dealt in as an article of trade, particularly from India. Among 
the numerous species of Cassia noticed by Roxburgh, this has 
not been alluded to, so far as we can discover; nor does it appear 
that Wallick or Carey, for so longatime residents of the East, 
* Delile. Description des series. Memoires sur l'Egypt tome iii. 
