KEY. BASED UPON LEAVES. 11 



ff . Subequal, sinuses 



Wide, lobes narrow and nearly entire ; leaves 5-9 in. long. 



38. QUERCTJ^ ALBA. 



Narrow, lobes wide and 

 mostly undulate or crenate-toothed ; leaves 2-3 in. long. 



160. Q. LOBATA. 

 Entire or nearly so and round or obtuse at apex. 



136. Q. GARRY ANA. 

 gr 2 . Very unequal, 

 h. The two lobes nearest the summit much the largest. 



92. QUERCUS OBTUSILOBA. 



h~. Lyrate-pinnatifid and sinuses extending 



Nearly to the midrib and roundish 39. QUERCUS MACROCARPA. 



Usually not over half-way to the midrib and more acute. 



06. Q. BICOLOR. 

 f 2 . Bristle-pointed ; sinuses 

 ff. Moderately deep and narrow; 



Lobes narrowing towards apex and mostly terminating in 1-3 bristle- 

 pointed teeth 15. Q. RUBRA. 



Lobes generally widening towards apex and terminating in 3-7 bristle- 

 pointed teeth 102. Q. CALIFORNICA. 



ff-. Deeper and broader ; lobes narrower 93. Q. TINCTORIA. 



</ ! . Deep, broad and rounded ; lobes very narrow; acorn 

 Ovoid-oblong, | immersed in a coarse-scaled cup. 



69. QUERCUS COCCINEA. 

 Flattened-globular, i immersed in a fine-scaled cup. 



94. QUERCUS PALUSTRIS. 

 e 4 . Broad, truncate at both base and apex, and with two spreading lobes on 



on each side 2. LIRIODENDRON TULIPIFERA. 



e 5 . Wavy and spinous- toothed, very thick 52. ILEX OPACA. 



e 6 Undulately crenate-toothed ; obovate-oblong, 



Slightly 'if at all pubescent beneath 67. QUERCUS PRINUS. 



Velvety pubescent beneath 116. QUERCUS MICHAUXII. 



e 1 . Sinuate-toothed, white-tomentose beneath 96. POPULUS ALBA, 



e s . Cut-serrate or sublobate with slender petioles ; 



Ovate, coarsely cut-serrate 83. PYRUS CORONARIA. 



Round-ovate, finely cut-serrate 86. CRAT^GUS COCCINEA. 



e 9 . Crenate-serrate ; petioles 1 in. or slightly less in length. 



82. PRUNUS CERASUS. 

 e 10 . Obscurely crenulate- toothed ; leaves 



Alternate, petioles long, mostly H in- r more. 



87. CORNUS ALTERNIFOLIA. 



Opposite, petioles short (less than 1 in.); involucral scales when fully 

 developed. 



Obcordate 88. CORNUS FLORIDA. 



Pointed at apex 185. CORNUS NUTTALII. 



e n . Undulate-serrate, ^-f in. long and bearing large scattered glands. 



154. DALEA SPINOSA. 



e ] -. Doubly crenate-serrate with glandular teeth 81. PRUNUS NIGRA. 



e' 3 . Doubly serrate, rhombic-ovate 9."). BETULA NIGRA. 



<l-. Main ribs several, palmately-veined, etc. 

 e. Rib single at first but soon sending off a strong vein on each side and 



leaves 3-lobed, 2-lobed or entire 32. SASSAFRAS OFFICINALE. 



-. Ribs three at first, but soon five or more by branching, leaves alternate, 

 base of petiole concave and fitting over the axillary bud, obscurely 



3-5 lobed with broad shallow sinuses 13. PLATANUS OCCIDENTALS. 



5-lobed with narrow and deeper sinuses 135. PLATANUS RACEMOSA. 



e 3 . Ribs 5-7 from commencement ; leaves 



/. Opposite, base of petiole subtending (not covering) the axillary bud. 

 ff. Moderately incised with broad lobes which are 



Sparingly sinuate-toothed 7. ACER SACCHARINUM, WANG. 



Irregularly serrate and notched 53. ACER RUBRUM. 



Sharply and finely doubly serrate 79. ACER PENNSYLVANICUM. 



