part 5
(1876).
=History=—The celebrated Bruce[978] during his journey to discover the source of the Nile, 1768-1773, found the koso tree in Abyssinia, observed the uses made of it by the natives, and published a figure of it in the narrative of his travels. It was also described in 1799 by Willdenow who called it _Hagenia_ in honour of Dr. K. G. Hagen of Königsberg.
The anthelmintic virtues of koso were investigated by Brayer, a French physician of Constantinople, to which place parcels of the drug are occasionally brought by way of Egypt, and he published a small pamphlet on the subject.[979] Several scattered notices of koso appeared in 1839-41, but no supply of it reached Europe until about 1850, when a Frenchman who had been in Abyssinia obtained a large stock (1,400 lb., it was said), a portion of which he endeavoured to sell in London at 35_s._ _per ounce_! The absurd value set upon the drug produced the usual result: large quantities were imported, and the price gradually fell to 3_s._ or 4_s._ per lb. Koso was admitted a place in the British Pharmacopœia of 1864.
=Description=—The flowers grow in broad panicles, 10 to 12 inches in length. They are unisexual, but though male and female occur on the same tree, the latter are chiefly collected. The panicles are either loosely dried, often including a portion of stalk and sometimes a leaf, or they are made into cylindrical rolls, kept in form by transverse ligatures. Very often the panicles arrive quite broken up, and with the flowers in a very fragmentary state. They have a herby, somewhat tea-like smell, and a bitterish acrid taste.
The panicle consists of a zigzag stalk, which with its many branches is clothed with shaggy simple hairs, and also dotted over with minute stalked glands; it is provided at each ramification with a large sheathing bract. At the base of each flower are two or three rounded veiny membranous bracts, between which is the turbinate hairy calyx, having ten sepals arranged in a double series. In the male, the outer series consists of much smaller sepals than the inner; in the female, the outer in the ultimate development become enlarged, obovate and spreading, so that the whole flower measures fully ½ an inch across. In both, the sepals are veiny and leaf-like. The petals are minute and linear, inserted with the stamens in the throat of the calyx. These latter are 10 to 25 in number, with anthers in the female flower, effete. The carpels are two, included in the calycinal tube; and each surmounted by a hairy style. The fruit is an obovate one-seeded nut.
Koso as seen in commerce has a light brown hue, with a reddish tinge in the case of the female flowers, so that panicles of the latter are sometimes distinguished as _Red Koso_.
[978] Travels, v. (1790) 73.
[979] _Notice sur une nouvelle plante de la famille des Rosacées, employée contre le Tænia_, Paris, 1822. The reader should also consult the excellent notice by Pereira written when the drug was first offered for sale in London. _Pharm. Journ._ x. (1851) 15; reprinted in Pereira’s _Elem. of Mat. Med._ ii.