52 BOTANY. 
G, the white Birch, Juniper, &c.; and above all, at G, there occurs Genista 
versicolor. Fg. 5 represents the distribution of American plants. Thus the 
palm is found up to A; arborescent ferns to B; the grape to C; cinnamon 
to D; oaks and the Mexican alder to EH; Pinus occidentalis to F ; maize to — 
G (probable snow line of Aconcagua); barley to H. On the eastern side, 
Pinus occidentalis at F, and the Mexican alder and oaks at G. Fig. 6 
illustrates the temperate zone of Europe; the grape, chestnut and walnut, up 
to A; to B, oaks, white birch, red birch ; to C, Pinus picea and abies; to D, 
Alnus viridis and Rhododendron ; to E, Salix herbacea ; F to G, Pinus rubra; 
to H, oaks ; and the chestnut, the grape, &c., down to the foot again. Fig. T 
refers to the Canary Islands: to A, Palms; to B, Cerealia and the grape; 
to C, Laurel trees; to D, Pinus canariensis; to EH, Spartium rubiginosum ; 
and to F, a species of Viola. Fig. 8 shows the distribution of plants in the 
frigid zone of Europe; Pinus sylvestris to A; the white birch to B; and to 
C, salix herbacea and lanata. 
SYSTEMATIC BOTANY, OR THE CLASSIFICATION OF 
PLANTS. 
It does not come within the scope of the present work to give a history 
of the rise and progress of the science of Botany, nor to enumerate the 
various systems of classification which have been propounded. We will 
merely state that such systems are either artificial or natural. The most 
important artificial system is that of Linnzeus, which, better perhaps than 
any other system affords an index to the genera. The objection to this 
- and to other artificial systems is, that genera and species of very different 
character are necessarily brought together, while their affinities and truly 
essential characters may be wholly opposite. Up to a comparatively recent 
period the system of Linnzus almost exclusively prevailed ; few botanists of 
the present day, however, make any other use of it than that of a key or index. 
In this system twenty-three classes are founded on the number, relative 
lengths, position, and connexion of the stamens; the orders in these classes 
depending on the number of styles, the nature of the fruit, occasionally the 
number of stamens, and the perfection of the flowers. The twenty-fourth 
class includes plants with inconspicuous flowers. The following is a tabular 
view of the system as analysed by Balfour. 
Tabular View of the Cuasses of the Linnean System. 
A. PHaxerocamia (Flowers present) : 
I, Stamens and Pisti] in every flower. 
1. Stamens free. 
a. Stamens of equal length, or not differing in certain proportions: 
Class I. Monandria with one  stamen. 
6“ II. Diandria “ two stamens. 
és lil. Triandria “ three «6 
$6 IV. Tetrandria “ four 66 
52 
