* 
530  ACCLIMATIZATION OF FOREIGN TREES AND PLANTS. 
the spleenwort from dry walls; even the royal "flowering- 
fern" from bogs; and some of the semi-alpine species will 
flourish with the exercise of a little care. One kind, how- 
ever, is almost invariably absent, and that the most widely 
distributed of all our ferns, the common break, a native of 
every county and almost of every parish in the country, but 
which can seldom be induced to remain a denizen of soil that 
has once been brought under man’s dominion. On the other 
hand some of the greatest favorites of our gardens, which 
display no coyness whatever in overrunning our flower-beds, 
are natives of countries where the climate presents very dif- 
ferent features to our own, or of very limited tracts of our 
own country, to which they seem strictly confined by im- 
passable barriers of soil or meteorological conditions. To 
take instances of the latter phetiomenphi: — There is no gar- 
den flower more cosmopolitan in its tastes, more certain to 
thrive under any conditions of light or heavy soil, sun or 
shade, care or neglect, even in the heart of a town, as its 
very name seems to indicate, than the London Pride. Yet 
the Saxifraga umbrosa is one of the most restricted in dis- 
tribution of our native plants. Abundant enough where it 
does grow, it is yet entirely confined to the moist equable 
climate of the hilly country in the south-west of Ireland and 
a few other similar localities, beyond-which it is never found 
in the wild state. Botanists will think themselves amply 
repaid for a toilsome day's march by gathering the beautiful 
Polemonium cæruleum in its native habitat among the calca- 
reous hills of the west of Yorkshire; yet the Jacob’ s Ladder 
is an ornament of every garden on the very stiffest part of 
the London clay. Probably ever y piece of cultivated 
ground, which contains a laburnum tree, produces each 
spring a plentiful crop of self-sown young trees, which come 
up without the least care or protection until destroyed in the 
process of weeding; yet the laburnum shows no disposition 
to take a place among the naturalized trees of our woods and 
hedges, although the seeds must often be carried there by 
