BOTANY. 
Orders, or families, are groups of nearly allied 
genera; just as genera are of related species. 
Thus, the rose, the raspberry and blackberry, 
with the strawberry, the apple, the thorn, the 
plum and cherry, &c., all agreeing in their gen- 
eral plan of structure, are brought together into 
one order or family, and termed Rosaceze ; that 
is, Rosaceous, or Rose-like plants. But the plum 
and cherry are evidently more nearly akin than 
the cherry and apple, &c.; and so the raspberry, 
blackberry, and strawberry on one hand, and the 
apple and thorn on the other, exhibit a closer 
relationship than that which connects them all 
in one common group. Hence they are respec- 
tively distinguished into groups of a rank inter- 
mediate between genera and orders, which are 
variously termed suborders or tribes.* 
Classes are groups of orders, having certain im- 
portant characters in common. Subclasses bear 
the same relation to classes, that suborders do to 
orders. 
By this regular subordination of groups, various 
degrees of relationship among plants may be ex- 
pressed; and upon this systematic botany essen- 
tially depends. Only four of these divisions are 
| universally employed, viz., Classes, Orders, Genera, 
_ and Species: these are common to all methods of 
| classification, and are always arranged in the 
| same sequence. 
But a more elaborate analysis 
is often requisite, on account of the large num- 
| ber of objects to be arranged, and the various 
degrees of affinity to be expressed ; when the ad- 
| ditional members, and if need be several others, 
_ are introduced; as in the following descending 
series : 
Classes, 
Subclasses, 
Orders, 
Suborders, 
Tribes, 
Subtribes, 
Genera, 
Subgenera, 
Species. 
An enumeration of the distinguishing marks, 
or points of difference, between one class or or- 
_* When the groups which an order embraces, are 
distinguished by characters of nearly equal value with 
those commonly employed for orders themselves, 
they aretermed suborders. ‘Thus, the plum, cherry, 
apricot, peach, &c., form one suborder of Rosacee ; 
the raspberry, blackberry, strawberry, cinquefoil, 
with the rose and other genera, constitute another 
suborder ; and the apple, the quince, thorn, &c., a 
third. The name of ¢ribe is applied to groups com- 
prised in a suborder (thus the rose constitutes a sep- 
arate tribe from the raspberry, strawberry, &c.), or 
to the primary divisions of an order, when they are 
not founded on characters of high importance. In a 
loose and popular sense, the name of tribe is fre- 
quently used as if synonymous with that of order or 
family. Thus we say, The pea-tribe, the fir-tribe, 
the violet-tribe, &c., merely as a simpler expression 
for ‘The family of which the pea, &e., is a repre- 
sentative,” 
493 
der, &c., and the others, is termed its character, 
The characters of the classes, and other primary 
divisions, embrace only those important points 
of structure upon which they are constituted : 
the ordinal character describes the general struc- 
ture of the included plants, especially of their 
flowers and fruit: the generic character points out 
the particular modifications of the ordinal struc- 
ture in a given genus; and the specific character, 
those less important modifications of form, rela- 
tive size, colour, &c., which serve to distinguish 
kindred species. A complete system of botany 
will therefore comprise a methodical distribution 
of plants according to their organization, with 
their characters arranged in proper subordina- 
tion; so that the investigation of a particular 
species will bring to view, not only its name 
(which separately considered is of little impor- 
tance), but also its floral structure, affinities, and | 
whole natural history. Such a system must of | 
course be natural, that is, the groups, of what- 
ever rank, must be composed of plants more 
closely related to each other than to any differ- 
ent groups, and so arranged that each shall stand, 
as far as practicable, next to those which it most | 
nearly resembles in structure. These conditions 
are so far fulfilled by the Natural system (which, 
sketched by the master-hand of Jussieu, and 
augmented by succeeding botanists, is now gen- 
erally adopted), as to render it on the whole far 
the readiest, as well as the only philosophical and 
satisfactory mode of acquiring any considerable 
amount of botanical knowledge ; notwithstanding 
its manifold imperfections, and peculiar difficul- 
ties. But the relationships of plants, even when 
appreciated by botanists, could not be made 
available for the purpose of classification, until 
Just views prevailed in vegetable organography | 
and physiology, which constitute the very foun- 
dation of systematic botany, but which have only 
recently been placed upon a philosophical basis. 
Hence the immortal Linnzeus, finding it impos- 
sible in his day to characterize the natural groups 
which his practised eye detected, proposed, as a 
temporary substitute, the elegant artificial scheme 
which bears his name. As this system is iden- 
tified with the history of the science, which in 
its time it so greatly promoted, and as most sys- 
tematic works have until recently been arranged 
upon its plan, it is still necessary for the student 
to understand it. Fortunately, its principles are 
so simple that a brief space will amply suffice for 
its explanation. 
Of the Artificial System of Linneus.—The object 
proposed by this system is merely to furnish an easy 
mode of ascertaining the names of plants; their re- 
lationships being left out of view, except that the 
species of a genus are always kept together, whether 
or not they all accord with the class or order under 
which they are placed. Its lower divisions, there. 
fore, viz. the genera and species, are the same as in 
a natural system. But the genera are arranged in 
artificial classes and orders, founded on some single 
technical character, and have no necessary agreement 
in any other respect. Hence they may be likened to 
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