Rural School Leaflet 1347 



the lobes are indentations, which botanists call sinuses. These sinuses are 

 variable and are often a help in identifying the different species. The 

 following is a key for identifying the different species of oaks. The use 

 of the term sinus in this key should be noted. 



White oak 

 KEY TO THE COMMON OAKS OF NEW YORK 



A . Acorns maturing in one season ; leaves with rounded lobes and rounded 

 sinuses white oak group 



1. Margin of leaf merely wavy-toothed, not cut so deeply as to be 



called lobed 



(a) Margin finely wavy-toothed Chestnut oak 



(b) Margin coarsely wavy-toothed, more pointed than in 

 chestnut oak Swamp white oak 



2. Margin of leaf distinctly lobed; one pair of broad sinuses cvitting 



nearly to the midrib of the leaf, so that the upper part of the 

 leaf is much heavier and broader-looking than the lower part. 

 Acorn with a mossy cup Bur oak, or mossy-cup oak 



3. Margin of leaf distinctly lobed, sometimes very deeply cut, 



with broad sinuses 



(a) Lobes usually seven or nine in number ; acorn pointed ; cup 



enclosing not more than one-fourth of the nut 



White oak 



