EFFECT OF SETTLEMENT UPON INDIGENOUS VEGETATION. 239 
sixteen of the total number of species, or nearly seventy per 
cent. of the whole. The grasses probably owe their wide spread 
to their being freely sown for fodder, and being wind-fertilised 
plants, they are able to more than hold their own against native 
flowering plants which are insect-fertilised, while they are them- 
selves the products of severe competition in the older continents, 
and so have an advantage over the native grasses. This more 
especially holds good in the moist coast district, and they do not 
so readily spread on the dry inland plains where the conditions are 
more or less adverse to them. 
The Composites probably owe their success to, first, their being 
capable of fertilisation by any insects ; second, to the large quan- 
tities of seed they produce ; and third, to the fact that many of 
them possess special apparatus for the dissemination of their seeds. 
The Leguminous plants spread partly because they are freely 
sown on account of their value as fodder, and partly because the 
undigested seeds are scattered far and wide by stock feeding on 
the plants. | 
The Labiates seed very freely, and some possess special means 
of spreading in their fruits. 
The Amarantacez, Chenopodiacez, and Polygonacez seed very 
freely, are self-fertilised, and have their seeds scattered by passing 
through the digestive canal of stock uninjured. They are also 
spread by ants which collect the seeds as food. The last of these 
three orders too, possesses fruits furnished with hooklets which 
cling to passing animals. 
The Cacti have edible fruits which birds eat and void the seeds 
in new localities ; their spines too, help them by protecting them 
from herbivorous mammals. 
