162 NEW ZEALAND PLANTS. 
the plant-world form the starting-point for classification. Unfortu- 
nately, these individuals are not all equal from the biological stand- 
point. Some reproduce their like, and groups of these — each 
individual producing individuals almost exactly the same as those 
produced by the remainder of the group—are self-breeding entities, 
all of common descent. True-breeding groups of this kind may be 
called ‘‘ little species.” Other individuals are hybrids, and usually 
their offspring differ in certain characters from the parents. Other 
individuals, again, though really identical, may look so different from 
one another, owing to their growing under different conditions, that, 
without experiment, it may be mere guesswork to pronounce them 
either similar or dissimilar. 
Frequently in certain groups of “little species” the individuals 
of these groups taken as a whole so greatly resemble one another 
that it is difficult to find good, easily recognizable marks by which 
the individuals of each group may be recognized and not confused 
with the individuals of the other groups. In order to meet this 
difficulty such closely related groups of “little species”? are united 
into one large group, which, notwithstanding that such a group 
consists of two or more distinct entities, is called a species. 
There are therefore in floras two distinct kinds of species, viz. : 
(1) The little species, which, however, is kept distinct as a species 
only if it has no extremely close relatives; and (2) the big or 
aggregate species, which is a combination of two or more little species. 
Between these two classes floras usually make no distinction, although 
they are obviously two quite distinct biological conceptions. 
In giving a definition of an aggregate species frequently no one 
plant found in nature is meant, but the description includes the 
characters common to all the little species making up the group, 
and the species is said to be “ variable.”’ Thus such a species is not 
a reality, but merely an idea. The realities are the little species 
which make up the aggregate: these really exist in nature. Where 
these units (the little species) of the aggregate species are recogniz- 
able, names may be accorded them as varieties, the variety thus 
really corresponding biologically to those species composed of one 
little species alone. There is thus nothing derogatory in the rank 
of ‘“‘ variety,” since it is equivalent to that type of species which 
comes true from seed but is kept by itself as a species since 
there are no closely allied little species with which it would be 
convenient to unite it. 
