Quercus Fagaceae 379 



1893. QUERCUS [Tourn.] L. Oak 



[Dyal, Sarah C. A key to the species of oaks of Eastern North America 

 based on foliage and twig characters. Rhodora 38 : 53-63. 1936.] 



Note: In collecting leaf specimens of oaks for identification, it should 

 be kept in mind that the foliage is variable. The leaves of seedlings, 

 coppice shoots, and vigorous shoots of old trees sometimes vary con- 

 siderably in size, form, and margin. Leaves in the shade on old trees 

 usually have the margins more nearly entire than the typical leaves. For 

 example, on the lower and inner branches of a pin oak, leaves may be 

 found whose lobes are not as long or longer than the undivided portion 

 of the leaf, and this character refers them to the red oak group. In the 

 case of Q. bicolor and Q. lyrata, while the pubescence of the under surface 

 of the leaves is normally a white or gray tomentum, the shade leaves 

 may be without the tomentum and may be green and merely pubescent. 



Mature leaves never with bristle tips; fruit maturing the first year; inner surface of 

 shell of nut glabrous; bark gray (except in no. 5), more or less scaly. (The White 

 Oaks.) 

 Leaves glaucous and glabrous beneath at maturity (rarely a specimen retaining its 



pubescence until maturity) 1. Q. alba. 



Leaves generally covered beneath with a dense, gray tomentum, often accompanied 

 by some long, simple or fascicled hairs, rarely the tomentum lacking on the 

 leaves of lower branches and then the surface more or less densely pubescent, 

 rarely a specimen with leaves pubescent only on the principal veins. 

 Primary lateral veins of the lower surface of the leaves regularly spaced or some 

 of the leaves with an irregular spacing; margins rather regularly sinuate- 

 dentate or with irregular shallow lobes in no. 3. 

 Shrubs; leaf blades mostly 5-10 cm long; teeth of blades usually fewer than 8 to 



a side; fruit sessile 2. Q. prinoides. 



Trees; leaf blades mostly more than 10 cm long; teeth of blades mostly more than 



8 to a side (except blades from the top of some trees of Q. Muhlenbergii) . 



Lower surface of leaves mostly with 4-10 pairs of lateral veins; veins of most 



of the leaves not all ending in teeth of the margin; blades usually not 



bilaterally symmetrical; fruit on peduncles longer than the petioles; one 



year old branches never corky 3. Q. bicolor. 



Lower surface of leaves mostly with 7-12 pairs of veins; veins all ending in 

 teeth of the margin; leaves essentially bilaterally symmetrical. 

 Apex of leaves of fruiting branches sharp-pointed, the sides of the apex 



usually forming an acute angle; fruit sessile or nearly so 



4. Q. Muhlenbergii. 



Apex of leaves of fruiting branches rounded or, if sharp-pointed, the angle 

 formed by the sides rarely an acute angle; fruit peduncled. 

 Leaves dark green above and generally velvety-pubescent to the touch 

 beneath; scales of cup free to the base; bark like that of white oak; 



trees of low ground 5. Q. Prinus. 



Leaves yellowish green and generally densely pubescent beneath but the 

 pubescence not velvety to the touch; scales of cup free only at the 

 tip; bark like that of the red oak; trees of high ground, usually on the 



crests and slopes of sandstone and knobstone ridges in Indiana 



6. Q. montana. 



Primary lateral veins of the lower surface of the leaves not regularly spaced; 

 leaves deeply lobed or pinnatifid. 

 Branchlets densely pubescent; leaves strongly obovate in outline; blades mostly 

 less than 15 cm long, cut into 5 principal lobes, the two upper lateral lobes 



