316 PRACTICAL BOTANY 



Pine tar, rosin, and oil of turpentine (commonly called spirits 

 of turpentine) are valuable products, obtained in this country 

 principally from the long-leaf southern pine (Fig. 261). 



Timber is the principal product of our conifers. At present 

 more than three fourths of the timber supply of the United 

 States is furnished by various conifers, especially pines. Dur- 

 ing the early history of this country the white pine (Pinus 

 strobus) was almost our only important soft wood. Now the 

 long-leaf pine (Pinus palmtris), the loblolly pine (Pinus tcedd) 

 of the southeastern states, and the bull pine (Pinus ponder- 

 osa) of the Pacific coast and the Rocky Mountain region are 

 largely utilized. 



Other important coniferous timber trees are two eastern 

 species of true spruce (Picea), the western Douglas fir (Fig. 

 262), two other western firs (Abies'), and the southern bald 

 cypress (Taxodium). Considerable redwood (Sequoia semper- 

 virens) lumber is made, though preservation of redwood for- 

 ests is limiting their output. The cypress, larch, and most of 

 the cedars, because of their durability, afford highly valuable 

 timber for all kinds of out-of-door work, especially for posts 

 and railroad ties. Red cedar is employed in making moth- 

 proof chests, and is almost the only wood used for lead pencils. 



Although the lightness of most coniferous woods makes 

 them worth less for fuel (when bought by the cord) than the 

 heavier deciduous-leaved species, still immense quantities of 

 coniferous woods are used for fuel. 



289. The Cycadales. This group includes nine genera. These 

 are found in tropical and semi-tropical countries, and some of 

 them are found only within comparatively small areas. The 

 stem is straight, usually unbranched, and bears at its tip a 

 crown of leaves, each of which bears many hard and rigid leaf- 

 lets (Fig. 263). In some species the stem is almost or entirely 

 embedded in the earth, and in such cases it is like a long tuber. 

 The stem is used by the plant as a storage region for starch. In 

 some countries these stems are collected for the starch, which 

 after extraction is sometimes called sago, though the usual sago 



