16 NEW ZEALAND PLANTS. 
that of Stewart Island, though similar in appearance, have, excepting 
ferns, but few species in common; also, the number of species in 
the latter is considerably smaller than in the former. This fact, 
then, stands out clearly: that the general appearance of a plant- 
community throughout its range need not depend upon its having a 
uniform floristic composition. It follows, then, that for such wide- 
spread plant-communities as forest and tussock-grassland the primary 
classification cannot be based upon their floristic composition, since 
there is no floristic uniformity, but upon their always consisting of 
plants of certain forms. Combinations of trees, shrubs, climbing- 
plants, and ferns make up the forest for the most part; while 
tussock-grasses and other herbs of various kinds, together with cer- 
tain shrubs of rather unusual form, make up the grassland community. 
Perhaps the matter of classification of plant-communities may 
be made clearer to the general reader by a consideration of an area 
of farmland. Taking, then, the case of an ordinary mixed farm, 
the plant-covering falls into the two categories of grassland and 
crop. Also, there may be a plantation of pine-trees near the farm- 
house. The crop may consist of cereals or “roots.” In the case of 
the grassland, the dominant grass of the meadow may be rye-grass, 
cocksfoot, meadow-foxtail in drained swamps, or danthonia on a 
rather barren hillside. Now, all these grass-communities resemble 
one another to no small extent, but they differ in their general 
appearance so completely from the grain or root crops or the planta- 
tion of pines that they must be united into a community distinct 
from all these, to be known as meadow, whose special characteristic 
is that the dominant plant is of the ordinary grass form. On the 
other hand, the smaller communities of this meadow are distinguished 
by the fact that their dominant members are different—rye-grass, 
cocksfoot, &c. So, too, in the case of the crop, it might be wheat, 
or oats, or barley ; or, if of roots, swedes, soft turnips, or mangolds. 
Here, too, the cereals would form as a whole the large plant- 
community, their general form being the same; and so, too, with 
the roots as a whole, for a similar reason; but wheat, oats, or 
swedes would each be a smaller community, because each is @ 
distinct kind of plant. 
The large and the small communities cited above may be called 
plant-formations and plant-associations respectively. A plant-formation 
is distinguished by its general appearance—a result of the special 
