_Cortex Peruvianus_, _Cortex Chinæ_; _Cinchona Bark_, _Peruvian Bark_;
F. _Ecorce de Quinquina_; G. _Chinarinde_.
=Botanical Origin=—The genus _Cinchona_ constitutes together with
_Cascarilla_ (including _Buena_ and _Cosmibuena_), _Remijia_,
_Ladenbergia_, _Macrocnemum_, and about 30 other nearly allied genera,
the well-characterized tribe _Cinchoneæ_ of the order _Rubiaceæ_. This
tribe consists of shrubs or trees with opposite leaves, 2-celled ovary,
capsular fruit, and numerous minute, vertical or ascending, peltate,
winged, albuminous seeds.
(=A.=) _Remarks on the genus._—The genus _Cinchona_ is distinguished by
deciduous stipules, flowers in terminal panicles, 5-toothed superior
calyx, tubular corolla expanding into 5 lobes fringed at the margin.
The corolla is of an agreeable weak odour, and of a rosy or purplish
hue or white. The fruit is a capsule of ovoid or subcylindrical form,
dehiscing from the base (the fruit-stalk also splitting) into two
valves, which are held together at the apex by the thick permanent
calyx. The seeds, 30 to 40 in number, are imbricated vertically;
they are flat, winged all round by a broad membrane, which is very
irregularly toothed or lacerated at the edge.
The Cinchonas are evergreen, with finely-veined leaves, traversed by a
strong midrib. The thick leafstalk, often of a fine red, is sometimes a
sixth the length of the whole leaf, but usually shorter. The leaves are
ovate, obovate, or nearly circular; in some species lanceolate, rarely
cordate, always entire, glabrous or more rarely hirsute, often variable
as to size and form in the same species.
Among the valuable species, several are distinguished by small pits
called _scrobiculi_, situated on the under side of the leaf, in the
axils of the veins which proceed from the midrib. These pits sometimes
exude an astringent juice. In some species they are replaced by tufts
of hair. The young leaves are sometimes purplish on the under side; in
several species the full-grown foliage assumes before falling, rich
tints of crimson or orange.
The species of Cinchona are so much alike that their definition is
a matter of the utmost difficulty, and only to be accomplished by
resorting to a number of characters which taken singly are of no great
importance. Individual species are moreover frequently connected
together by well-marked and permanent intermediate forms, so that
according to the expression of Howard, the whole form a continuous
series, the terminal members of which are scarcely more sharply
separated from the allied genera, than from plants of their own series.
As to the number and value of the species known, there is some
diversity of view. Weddell, in 1870, enumerated 33 species and 18
sub-species, besides numerous varieties and sub-varieties. Bentham and
Hooker, in 1873, estimated the species as about 36.
Kuntze, in the book quoted at the end of the present article, proposed
to reduce all the species to the four following:
1. _Cinchona Weddelliana_ O. Kuntze, nearly answering
to _C. Calisaya_ Weddell.
2. _C. Pavoniana_ O. Kuntze, including _C.
micrantha_ Ruiz and _Pavon_ and several allied
plants.
3. _C. Howardiana_ O. Kuntze, constituted of _C.
succirubra_ Pavon and a few other species of former
authors.