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TEXTBOOK OF BOTANY 



dies, and wagon parts. Various species of the walnut family are culti- 

 vated for their nuts and as ornamentals (Fig. 341). 



Fig. 341. Catkins of staminate flowers on a branch of the bhick walnut 



(Jiiglans nigra). 



The birch family ( Betulaceae ) . This well-known family has 6 genera 

 and some 100 species. The commonest representatives are birches, al- 

 ders, iron wood, hornbeam, hazelnuts, and filberts; and some of these 

 occur as fossils in the Cretaceous rocks. The plants are either trees or 

 shrubs varying from a few inches in height in some arctic birches to 

 occasional specimens 120 feet high and 3 or 4 feet in diameter. The 

 bark is often thin and mav be removed in papery sheets. 



The birch familv is especiallv valued for its superior wood (furni- 

 ture, interior finishing, floors, athletic goods), its bark (canoes, baskets), 

 its nuts, and its ornamental uses. The inner bark is quite nutritious and 

 important in the food of certain wild animals. 



The beech or oak family (Fagaceae). In many localities within the 

 deciduous forest areas the beech, oak (Fig. 342), and chestnuf^ are 

 some of our best-known trees. The trees are often of magnificent pro- 

 portions, well over 100 feet in height and with trunk diameters of 6 



^ Because of the ravages caused by the chestnut bhght this statement is no longer true, 

 since the chestnut has been practically destroyed by the disease. 



