(A larger monograph by Lloyd can be found at: http://www.swsbm.com/ManualsOther/Strophanthus-Lloyd.PDF)
The genus Strophanthus, which produces this drug, is chiefly African, belonging to the apocynaceae and the tribe echitideae of this order, distinguished from the other tribes of the order chiefly from having the anthers united after the manner of the asclepiadaceae. Index Kewensis mentions seventeen species, Bentham and Hooker eighteen species, Pax (495) twenty-five species, and the genus is being rapidly augmented as the flora of Africa becomes better known. Plants of the genus have usually woody stems, emitting a milky juice when wounded, and are generally twining vines. The seed of commerce is probably collected from various species indiscriminately, which have been classified and differentiated by Pax (495), Planchon (512), Hartwich (304), Holmes (322), Blondel (80), and others. Space will permit us to mention only the two species which are acknowledged to be the principal source of the drug.
Strophanthus hispidus, D. C., was one of four species described by De Candolle as early as 1802, and is the species to which the drug was first ascribed. Its habitat is Senegambia and Guinea and other parts of Western Africa. The stem is a twining, milky shrub, with opposite hirsute leaves. (Hence the name hispidus, Latin for bristly, hairy.) The seed, which bears a slender style terminating in a plumose pappus consisting of long hairs, (Hartwich calls special attention to the fact that the hairs of Strophanthus seed are very sensitive to moisture, spreading horizontally in dry air, and becoming erect in moist atmosphere. He suggests that the pappus would thus make an hygrometer sufficiently sensitive for practical purposes.) is the part used in medicine.
As stated before, the genus Strophanthus was established by De Candolle as far back as the year 1802. It was not until the early sixties, however, that the drug came to the general notice of Europeans as being one of the arrow poisons used among the African native tribes, there being two kinds of arrow poisons derived from this source. A poison was prepared on the west coast of Africa (Senegambia, Guinea, and Gaboon) called inee or onaye, which is derived from Strophanthus hispidus, D. C. This is on the authority of Hendelot, who observed the plant yielding this poison in Senegambia at the River Nunez (246). A specimen of this arrow poison was sent to Europe and investigated by Pelikan in 1865. (Comptes Rendus, 1865, vol. 60, p. 1209.)
On the east coast of Africa the kombe or gombe poison was in use in the Manganjah tribe, located near Lake Nyassa on the banks of the River Shire, a tributary of the Zambesi River. Consul Kirk in Zanzibar, in 1861, established that this poison originated from a strophanthus species, and forwarded specimens to Professor Sharpey in England for the purpose of investigation (246). Subsequently, in 1865, Livingstone's famous reports brought the kombe poison to a more general notice among the Europeans (387).
This species of strophanthus was at first considered identical with S. hispidus, D. C., but the plant was shown by Oliver in 1885 to be distinct from the latter, and justified the establishing of a new species, Strophanthus kombe.
The physiological features of the drug as a powerful cardiac were recognized by the first investigators (Sharpey, 1862; Pelikan, 1865; Fraser, 1871). Livingstone reports the observation of Consul Kirk that the poison remarkably reduced the pulse, but the drug was not authoritatively recognized by the medical profession until about the year 1885. In this connection it is interesting to note that in Somali-land, Africa, the native, in order to establish the virulence of the poison, scrapes the skin from his own arm until the blood flows, when he applies the poison to the lower end of the bloody pool and watches the coagulating effect, from below upward. To the firm of Burroughs, Wellcome & Co., London (677-678), is largely due the position that Strophanthus occupies in the medical lore of the present day, this being due chiefly to the efforts of Mr. Henry S. Wellcome, through his friend, Henry M. Stanley, the African explorer.