CLASSIFICA TION. 
r 3 8 
Cohort 8. Rubiales=.co\i. 7 and order 256. 
9. Campanulinae—^2iX\. of coh. 9. 
10. Aggregatae— orders 257, 262 and 263. 
It will be noticed that the two German systems agree in 
making only two chief groups of Dicotyledons ; the English 
system, on the other hand, makes a third group, the Incom- 
pletae, which is decidedly artificial, separating for instance the 
Chenopodiaceae, &c. far from the Caryophyllaceae to which 
they are closely allied. In general, the composition of the 
smaller groups of orders is much the same in all systems ; the 
differences lie chiefly in the composition and arrangement of 
the larger groups, as is easily understood from what we have 
said above. The elementary student should not concern him- 
self with any system of classification until he is well acquainted 
with a number of orders (see p. 4): he should then carefully 
study the systems above given and endeavour to discover 
why their authors have placed such and such orders in the 
places assigned to them in the various systems. In this 
way he will gain an insight into the principles of classifica- 
tion. The relationships of many of the orders are discussed 
in Pt. II. When the student is familiar with 40 or 50 
orders, occupying different places in the system he adopts, 
he will be able to classify approximately any new order that 
may be presented to him, by determining its affinities to 
those he already knows. It must be clearly understood 
that the attempt to use the system to determine the order 
to which a plant belongs will only lead to difficulties unless 
the student is already familiar with typical orders from 
many parts of the system. In actual systematic practice, 
little if any use is made of the larger groupings, and the 
position of a plant in the system is recognised by its affinities 
to others whose positions are known. 
Identification of Natural Orders at sight. After 
a time, the student will find himself becoming able in many 
cases to recognise at a glance the natural order to which a 
plant belongs, and after a few years’ practice, he should be 
able in this way to classify most of the plants met with in 
the field or in a botanic garden. Sometimes the order can 
be recognised from its general habit, or from belonging to a 
limited group, e.g. water-plants or parasites, in other cases it 
can be identified with certainty only when in flower. 
