INTRODUCTION. XV 



reason why they are exceptions, are pointed out together 

 where they occur. But in this as in every other merely 

 technical division of the vegetable kingdom embracing 

 numerous and varied subjects, it is easy to define the 

 typical characters, but difficult to describe them in the 

 extremes and in exceptional cases. In the case of alpine 

 plants, any tangible definition of the class by its features, 

 apart from that commonly known as herbaceous, is 

 impossible. The terms herbaceous and alpine are em- 

 ployed arbitrarily in these pages, and in gardens, to de- 

 fine the same types of vegetation, as existing under dif- 

 ferent conditions in nature ; the former applies to the 

 general herbage of the plains of all countries similar to 

 our own in climate, and to that of those of the warmer 

 latitudes ; and the latter includes the general herbage 

 and minute shrubs that clothe the mountains of all quar- 

 ters of the earth. Beginning first to appear at the high- 

 est limits of cultivation, they ascend to the confines of 

 perpetual snow, where life of all kind ceases to appear. 

 In so vast a realm nature has scattered practically limit- 

 less stores of floral wealth. Much of it already lies within 

 our reach, tempting us to appropriate and make it our 

 own ; but in the wide untrodden mountain tracts in 

 many parts of the Old World, and in the unexplored 

 regions of the New, more may be expected to lie hid, 

 waiting only for the seeker in order to be found. But 

 in scanning even slightly the species of herbaceous and 

 alpine plants that are at hand in the botanic gardens or 

 in the nurseries of a few men who are bestirring them- 

 selves to make collections of them, we find ample variety 

 of habit and aspect, endless diversity and grace of foliage, 

 and exquisite types of flowers in every imaginable hue, 



