4 THE STUDY OF PLANTS 
7. Binomial nomenclature. To each of the different kinds of 
plants and animals which were known in his time, Linnzeus gave a 
name like the one above, consisting of two parts. In doing this he 
made universal a principle very generally followed in the common 
names with which we are most familiar. Thus we speak of the 
White Mulberry, the Red Mulberry, and the Black Mulberry. 
Translated into Latin, these become the botanical names, Morus 
alba, Morus rubra, Morus nigra—the adjective part, as will be 
noticed, following the noun Morus according to the rule commonly 
observed in that language. So among the different kinds of oaks we 
have Quercus alba, Quercus rubra, and Quercus nigra; and to certain 
of the willows have been given the names Salix alba, Salix rubra, 
and Salix nigra. It will be seen that as the same component occurs 
repeatedly in the different names (just as in the names of persons 
there are many Smiths, Browns, and Robinsons and many Johns, ~ 
Jameses, and Marys); so by adopting for plants the binomial or 
two-part system of naming, botanists are able to designate with 
perfect accuracy the many thousand kinds of plants, by means of 
a comparatively small number of words—a very much smaller — 
number in fact than would be required if each kind had to have a 
name consisting of a single word. Thus, in the examples given it 
will be noticed that six words serve for naming nine different kinds 
of plants. 
Another great advantage of the binomial method is that the 
name alone may tell quite a good deal about the plant, for, as we 
have seen, those sorts which resemble each other closely have the 
first part of the name identical. From this the reader would know, 
for example, that Quercus aquatica must be some kind of oak, and 
Salix sericea, some sort of willow. 
8. Species. Ordinarily, there is no danger of being mis- 
understood when we speak of such and such “sorts” or 
“kinds” of plants, in the way that people commonly do; 
but when we come to a careful study of plants we find among 
them such variety in the degrees of resemblance and differ- 
ence that the necessity arises for a more precise means of 
expressing ourselves. It thus becomes important to under- 
stand something of the distinctions which naturalists recog- 
nize between the different degrees of likeness among living 
things. 
When from a dozen seeds out of the same pod, say of a 
kidney-bean, we raise as many plants, there are twelve dis- 
tinct individuals no two of which are exactly alike in all 
particulars. Yet despite their individual differences, they re- 
