74 EFFECTS OF CLIMATE. 
the sea, is a beautiful and verdant garden, which is 
entirely surrounded by snows that never melt. This 
spot is covered with Alpine plants; and so luxuriant 
is the growth of the vegetation, that at certain sea- 
sons of the year the Swiss peasants drive their cattle 
over the great glacier of Mer de Glace for the sake 
of the delightful pasture the valley affords. 
In our own country, where so great a variety of 
climate is witnessed, it is probable that a greater 
variety of plants can be enumerated than in any other. 
Our gardens and conservatories are indebted for many 
of their finest ornaments to the far-off fields and woods 
of California, Mexico, and the territories west of the 
Rocky Mountains,— countries which combine within 
their range a climate varying almost from frigid to 
tropical, and exhibiting at the same season a corre- 
sponding difference in their floral productions. In 
the northern and western States, while the cold earth 
still lies locked in winter’s last embraces, the woods 
of the south are teeming with life, the fields are 
clothed with the verdure of spring, and the air is 
scented with the perfume of flowers. But in the 
regions of tropical Mexico, and the everglades of 
Florida, vegetation becomes so entirely changed in 
its character, as to maintain a more uniform appear- 
ance at all seasons of the year. 
Most plants, whose roots are perennial, have a 
period of rest, during which they cease to grow; in 
the north, this is usually indicated by the falling of 
the leaves, and the plant assuming the appearance 
of being dead; in the tropics it is marked by the 
