SPERMATOPHYTA GYMNOSPERMS ' 327 



Fig. 127. Hemlock (Tsuga 

 canadensis). A common forest 

 tree of Northern North America. 

 Contains resin and the usual 

 principles found in these resins. 

 Said to be injurious. 



CONIFERAE 



Resinous trees or shrubs generally evergreen leaves, entire or scale-like; 

 wood consists mostly of tracheids marked with large depressed disks; tracheae 

 only present near the pith and in the leaves; perianth none; flowers monoecious; 

 stamens several, together, subtended by a scale; anthers 2-7 celled; pollen grains 

 frequently of three cells, one fertile and two inflated; ovules with two coats, 

 borne solitary or together on the surface of a scale, straight or partly inverted ; 

 fruit a cone, usually papery, but in some instances fleshy, sometimes berry-like; 

 seeds winged or wingless; endosperm abundant, fleshy or starchy; embryo 

 straight and slender; cotyledons 2 or more. About 25 genera and between 275 

 and 300 species. They include the Podocarpus of the tropical regions, the Taxus 

 or Yew, the Norfolk Pine (Araucaria excelsa and A. brasiliana), frequently 

 cultivated, the White Cedar (Cupressus Lawsoniana) of California, the Cupress- 

 us nootkatensis of the northwest coast, the White Cedar (C. thy aides) which 

 occurs in swamps, in the East; the genus Picea consisting of the spruces, Nor- 

 way Spruce (P. Engelmannii) , Tideland Spruce (P. sitchensis), one of the larg- 

 est trees in Oregon and Washington; the Douglas Fir (Pseudotsuga Douglasu), 

 one of the most valuable of the North American conifers, found in Washington, 

 Oregon and California and in the Rocky Mountains; the Hemlock (Tsuga 

 canadensis), abundant in North America, and the source of Canada or Hemlock 

 Pitch, the bark containing an abundance of tannin ; the leaves are said to be 

 abortive ; the Tsuga heterophylla of the Pacific coast which produces a valuable 

 lumber; the Balsam Fir (Abies balsamea), which furnishes a kind of balsam 

 that contains four acid resins and a volatile oil; the Black Fir (Abies concolor}*. 



