312 



PEACTICAL BOTANY 



The coniferales are again divided into two families, the 

 Pine family and the Yew family. Practically all gymnosperms 

 commonly known in most parts of the United States belong to 



the Pine family. In addi- 

 tion to the widely distrib- 

 uted genus Pinus already 

 discussed, there are the 

 spruces (^Picea), which 

 have short, stubby needle 

 leaves (Fig. 257, A and5), 

 close-set branches, and 

 long, generally pendent 

 cones. The spruces are 

 among our most beauti- 

 ful trees, and apprecia- 

 tion of them is shown 

 by the extent to which 

 they are being planted 

 for ornamental purposes. 

 Their detailed structure 

 and reproductive proc- 

 esses resemble those of 

 pines. The hemlock trees 

 (Tsuga and Paeudotsuga) 

 (Fig. 257, C), fir trees 

 (^Abies'), and the southern 

 bald cypress (^Taxodiuni) 

 are members of this fam- 

 ily. Bald cypress is one 

 of the gymnosperms that 

 can live in swampy places. 

 Its roots spread enor- 

 mously, near the surface. 



Fig. 259. A large cedar tree {Thuja occi- 

 dentalis) 



The size of this tree is indicated by a com- 

 parison with the man standing at tlie right. 

 Photograph by the Keyser Photo Company, 

 Spokane, Washington 



Often from these roots when in swampy regions there grow 

 upward the peculiar, stump-like, woody structures (Fig. 19) 

 known as the " cypress knees." The central tissues of these 



