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POPULAR SCIENCE MONTHLY. 



as of the oaks, where we have the rounded lohed leaf of the 

 white oak, the pointed lobed red- oak leaf, and the obovate, ever- 

 green leaf of the red oak, with numerous transitional and deriva- 

 tive shapes. In the maples, too, the typical three-lobed, deeply 

 indented leaf branches out into a great diversity of forms, all 

 easily referable, however, to the primitive one, the peculiarities 

 of which are dependent upon the depth, the number, and the mi- 

 nuteness of the notchings. Another series of sports is shown in 



Fig. 5. — Live Oak. 



the birch leaves, where the pointed, serrated leaves of the black 

 and yellow birch are quite different in shape and general appear- 

 ance from the pointed, much-notched, glossy, isosceles-triangled 

 leaves of the white birch. This tree has other marked character- 

 istics. "Notice the bough where it joins the white trunk; this 

 triangular brown patch below the branch is always present in 

 any tree of any age. The leaf stem is slender, rather long, and 

 not downy ; the leaf (often growing, as in my sketch, in pairs) is 

 very smooth and shiny on both sides ; also, the stem being slen- 

 der the leaf shakes with the slightest breeze, and its varnished 

 surface, reflecting the sunlight, breaks it into shifting, sparkling 

 green fire." 



Another series of sports may be studied in the leaves of the 

 same tree, as the sassafras, of which three plainly marked shapes 

 may be found on the same twig, and the mulberry similarly char- 



