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AMERICAN MUSEUM GUIDE LEAFLETS 



-\- -Chambered 

 Pith 



FIG. 71. BUTTERNUT TWIG 



Longitudinal section to show the 

 chambered pith 



the top. This 

 tree, natural- 

 ized from Eu- 

 rope, is very 

 common along 

 streams and 

 marshes. The 

 many nati ve 

 varieties of 

 w i 1 1 o w a r e 

 difficult of rec- 

 ognition even 

 when they have 

 flowers or 

 leaves. 



2. Ameri- 

 can Aspen 

 i Popvlus trem- 

 uloidesMichx. . 



The twigs of the American aspen are greenish gray 

 and smooth. The pointed buds are long and covered 

 with glossy, gummy scales. The tree is a small one 

 with smooth greenish gray hark. 



Lar^e-toothed Aspen {PopuLus grandidentata 

 Michx.) has the same smooth greenish gray hark 

 as has the American aspen, but is a tree ol 

 ^mailer size. lis pointed buds are downy 

 instead of smooth and they extend at right angles 

 from the twig. 



Balsam Poplai <r<>i>itlux balsamifera L.i can 



he recognized by its coarse, ridged twig- and by the large sticky buds 



which have an unusually sweet odor. 



:;. Sycamore, Plane-tree, or Buttonwocd (Platanus occidental-is L.). The 



light-colored smooth twigs are rigid in appearance. The conical hrown 



buds are in the centers of the leaf scars, being formed within the hollow 



bases Of stems and not showing until the leaves fall (Fig. 66). The outer 



board-like scale covers light-brown silky scales of great beauty. The 



tree can he known by the bark which comes off in plates, leaving smooth 

 green or white spots (Fig. 67). The balls of frt.it hang on the tree all 

 winter. 



FIG. 70. BLACK WALNUT 



Leaf and flower 



buds. The leaf seals 



lack the downy ridge 

 conspicuous in butter- 

 nut 



