164 NEW ZEALAND PLANTS. 
while in some cases names at first thought to be suitable have proved 
to be quite the contrary. Notwithstanding this, the rules of modern 
botany demand that a specific name once given must stand for ever, 
even where the name is quite inappropriate ; even if the plant had 
originally been put in a wrong genus—a common enough circumstance 
—the original specific name must be used. A name, then, is now 
considered merely as a label and nothing more, and need have no 
meaning whatsoever. | 
Another matter which must be remembered is that generic differ- 
ences in the seed-plants generally depend on the structure of the 
flowers, and not on the form of the leaves. That a plant has leaves 
like a willow does not constitute it a willow; similar plant-form, as 
has been already shown in this book, occurs amongst plants quite 
unrelated. Leaves, however, amongst other characters, are made use 
of as marks of specific differences, and in many instances a plant can 
be readily identified from its leaves alone. 
Classification goes still further. A number of related genera 
make a family—formerly called a “ natural order ’—and still wider 
subdivisions are established, until such fundamental divisions of 
the plant kingdom are reached as—slime-fungi, algae, fungi, liver- 
worts, mosses, ferns, conifers, seed-plants with one seed-leaf in the 
seedling (monocotyledons), and seed-plants with two seed-leaves 
in the seedling (dicotyledons). 
The families are now most frequently arranged according to the 
manner in which they are supposed by some to have originated, the 
more simple coming first and the more complex last. Thus amongst 
seed-plants the pine-tree family begins the list, and the daisy family 
completes it. It must not be forgotten that this arrangement is 
hypothetical only, and that, although the monocotyledons come 
early on in the list, there is a good deal of evidence that they 
have originated from the dicotyledons, and not wice versa. With 
but few exceptions the rules of botanical nomenclature order the 
names of families to end in aceae. Thus the student must write 
Violaceae, not Violariae ; Scrophulariaceae, not Scrophularineae ; and 
so on. But Compositae, Umbelliferae, Palmae, Cruciferae, Labiatae, 
Leguminosae, and Gramineae are allowed. 
Considering the seed-plants alone, New Zealand has some 1,620 
species, about four-fifths of which are found nowhere else in the 
world, the number varying according to the computer’s conception of 
