ON THE CULTURE OF WILD FLOWERS AND PLANTS. 
87 
parts of fructification forward to nearly the natural size ; and then 
the full expansion, the act of fructification, and the after process 
of maturing and ripening the seeds, are effected by the agency 
of the sun and of the atmosphere. This appears to be the 
severest labour which a plant has to perform, and in those ex¬ 
tremes of season to which we allude the plant passes into a state 
of repose ; which is more and more marked in proportion as the 
drought and rain are more completely confined to their own 
periods. 
The third circumstance, and the only other one which we shall 
mention, is the natural atmosphere of the plant, or the air in 
which it grows and flowers best. This is much more varied than 
either of the two former; and we find it not only in the same 
country, but in very limited distances, in all countries which 
have the surface much diversified, and are exposed to winds 
blowing from surrounding districts of varied character. Thus 
some plants thrive well only in the rank and damp air of fenny 
and marshy places ; others thrive well only in shaded situations ; 
some love the open glade, where the air is balmy and pure ; and 
a few thrive best in the keen exposure on the mountain, and can 
with difficulty be kept alive in any place which, according to our 
common but erroneous views, is better adapted for vegetation. 
In Britain, the samphire upon the rock near the water line of 
the sea, and the lichen on the mountain-top, may be regarded 
as the extremes of vegetation, in respect both of habitat and of 
character; and though these plants had never so many charms for 
the florist, not one of them could be kept alive in his grounds. 
This extends to some little elevation in plants which were exposed 
to the sea ; and in mountain plants, though they vary in suscepti¬ 
bility to culture, the range is considerably greater. Therefore, 
were we to attempt the cultivation of our wild flowers, we should 
be confined to a certain portion of the middle of the series, as 
respects elevation above the level of the sea. 
But this elevation is not all; for plants have a geological dis¬ 
tribution as well as a distribution in altitude and exposure. The 
plants of the chalk soils will not, for instance, even in the close 
vicinity, and at nearly equal elevation, grow upon the sandy 
moors ; and the stunted heaths with which the latter are covered 
will not grow on the chalk. Even where the tertiary formation 
is the upper soil, we have great varieties in the predominating 
