THE TRUE PINES. 141 



are much thickened or swollen at their exterior terminal part.* The 

 form this part assumes differs in the different species, and is, therefore, 

 regarded by Botanists as an important character in the determination 

 of species. In some species this exterior terminal part of the scale is 

 regularly pyramidal and sharply pointed, sometimes it terminates in 

 hooked prickle ; in others it is simply a rounded protuberance or umbo, 

 while in the Strobus and Cembra sections it is almost smooth. 



The Pines include more species than any other genus in the Order, 

 and are distributed over a greater geographical area. Not many 

 more than half of them are hardy in Great Britain, and the number 

 available for planting may be diminished by the rejection of several 

 kinds, chiefly American, that possess no qualities to recommend them 

 for horticultural or arboricultural purposes. 



The economic value of the Pines is very great. Many species 

 afford timber of the highest importance in constructive work, and Pine 

 timber is the staple article of commerce with many ports of northern 

 Europe and British North America. The secretions of many species are 

 also very abundant, from which pitch, tar, turpentine, and resin are 

 flB^ied in immense quantities. The products and principal uses of the 

 most important species will be noticed under their descriptions. In 

 arboriculture, as in landscape planting, some of the most ornamental and 

 picturesque of trees are to be found among the Pines, while other 

 species are greatly valued as nurses for more tender trees — for forming 

 screens, &c. So various are the soils and situations in which the 

 different species occur in their native countries, that there is scarcely a 

 spot for which one or other kind is not suitable ; thus, the Scotch or 

 wild Pine grows on the bleakest hills ; Pinus Pinaster flourishes in 

 shallow sands near the sea-shore ; P. rirjida attains its greatest per- 

 fection amidst the Cedar swamps of Virginia ; P. ponderosa grows 

 in the arid plains of Utah, where no other vegetation exists ; and the 

 Scrub Pine (P. Bariksiand), straggles over the rocks in the cold and 

 sterile countries east . of Hudson's Bay. 



The Pines admit of a division into three Sections, according to tho 

 number of leaves in a sheath, thus — 



1. BiNiE, with two leaves in each sheath. 



2. Tern2E, with three leaves in each sheath. 



3. Quinji, with five leaves in each sheath.} 



* This part is called, in the language of Botany, the apophysis. 



t We adopt this Sectional Division on account of its obvious simplicity, and as being 

 that most available for practical uses. The true affinities of the Pines will be best sought 

 for in the fructification, to which the number of leaves in a sheath can only be regarded as 

 a subordinate character-. 



