68 



nia which is without foliage in winter. The subjoined key gives 

 the characteristics of the genera commonly found in Pennsylvania: 



KEY TO THE GENERA. 



Page 



1. Fruit a dry cone with winged seeds, 2 



1. Fruit a fleshy, round, dark-colored berry with bony seeds, Juniperus 



2. Leaves linear to needle-shaped, not closely overlapping; cone-scales numerous; buds 



scaly, 3 



2. Leaves scale-like, closely overlapping; cone-scales few; buds not scaly, 7 



3. Leaves in bundles of two or more except on young seedlings and on terminal twigs 



of Larix, 4 



3. Leaves solitary, 5 



4. Leaves persistent, 2-5 in each bundle, Pinus 6 



4. Leaves deciduous, more than 5 in each cluster, Larix 7 



5. Leaves flattened, whitish on lower surface, 6 



5. Leaves 4-angled, needle shaped, Picea T 



6. Leaves with leaf -like stalks, about 2/5 of an inch long; twigs rough; cones small 



with persistent scales Tsuga 



6. Leaves without leaf -stalks, usually 4/5 of an inch or more in length; twigs smooth; 



cones large with deciduous scales, Abies 8 



7. Leaves less than J of an inch long; twigs rather slender, not prominently flattened; 



cones globular with shield-shaped scales which do not overlap, Chamaecyparis 8 



7 Leaves i of an inch or more in length; twigs rather prominently flattened; cones 



elongated with 8-12 overlapping scales Thuja 8 



THE PINES— PINUS (Tourn.) L. 



This genus comprises more species than any other belonging 

 the Pine family. About 70 species are known in the world, 34 

 which are found in North America and 6 in Pennsylvania. Of th 

 34 species in North America, 13 are found in the eastern part an 

 21 in the western part. Besides the native Pines a number of exoti 

 species have been planted extensively for ornamental, and locall; 

 for . forestry purposes. The commonest exotic species are Scotc 

 Pine (Pinus sylvestris, L.) and Austrian Pine (Pinus Laricio vai 

 austriaca, Endl.). 



The Pines are adapted to a wide range of climate and soil. C( 

 tain species may be found bordering streams and lakes or close f 

 the ocean front while others are confined to mountain tops wher 

 they ascend to the timber line. This adaptability makes some c 

 the species of considerable economic value even though they ma 

 produce no wood of commercial importance. They can be used fo 

 afforesting mountain slopes where protection forests are to be forme 

 and maintained, and to reclaim sand barrens. 



The Pines are generally trees, rarely shrubs, and of considerabl 

 commercial importance on account of the excellent quality and larg 

 quantity of major and minor forest products which they yield. Se^ 

 eral species of Pine have always been foremost in the estimation c 



