16 KEY, BASED UPON FRUIT. 



C 4 . Nut hard, single coat and furnished with an involucral cup or covering, 

 d. Ovoid oblong or ellipsoidal, surrounded at its base with an involucral cup 



(Quercus), acorn borne 

 e. On the new wood of the season , cup 



/. Less than enveloping the oval acorn 136. QUERCUS GARRYANA. 



/*. About i enveloping the small, ovoid nut; ccales thin and appressed. 



68. Q. MUHLENBERGII. 



/ 3 . About enveloping the nut 



gr. Thick, scales very roughly tubercled, edge of cup rather inturned 



after shedding the nut ; nut usually long-ovoid 38. Q. ALBA. 



gr 2 . Thinner, scales thinnish ; leaves 



Deciduous; peduncles shorter than petioles. 



67. QUERCUS PRINUS. 

 Subpersistent; acorns sessile or nearly so. 



137. QUERCUS AGRIFOLIA. 

 f 4 . Scarcely enveloping the oblong-ovoid nut about 1 in. in length. 



116. QUERCUS MICHAUXII. 



/ 6 . About | or more enveloping the nut; peduncles longer than the 

 petioles ; nut 



f in. long, light-brown 66. QUERCUS BICOLOR. 



^ in. or less long, dark brown 117. QUERCUS VIRENS. 



f 6 . About or more enveloping the nut ; peduncles 



g. Longer than the petioles 66. Q. BICOLOR. 



gr 2 . Shorter than the petioles ; scales 



Very loosely appressed, forming a moss-like fringed margin of 



CUp 39. Q. MACROCARPA. 



More closely appressed and not forming a moss-like fringe. 



92. Q. OBTUSILOBA. 



e 3 . On wood of the preceding season (subgenus Melanobalanus); cup 

 f. Very shallow, almost flat and with long-linear recurved scales. 



138. QUERCUS DENSIPLORA. 

 / 2 . Saucer-shaped, enveloping the nut, which is 



g. Ovoid-oblong, about 1 in. long 15. Q. RUBRA. 



gr 2 . Flattened-globose; leaves 



Sinuate-pinnatifid with wide sinuses 94. QUERCUS PALUSTRIS. 



Obovate-spatulate, entire 118. QUERCUS AQUATICA. 



/ 3 . Top-shaped, enveloping the acorn ; scales thin and coarse 



Inner bark of tree reddish 69. Q. COCCINEA. 



Inner bark yellowish 93. Q. TINCTORIA. 



C? 2 . Club-shaped, short, surrounded with stiff hairs, tipped with the persistent 

 recurved style and arranged in globular heads, which are 



Solitary 13. PLATANUS OCCIDENTALS. 



2-7 together in a moniliform spike 135 PLATANUS RACEMOSA. 



d?. Achenium-like, small and borne in short catkins, 



Inclosed in a membranous inflated sac, catkin hop-like. 



41. OSTRYA VlRGlNICA. 



Subtended by an enlarged leafy bract . . . .42. CARPINUS CAROLINIANA. 

 C 6 . Nut-like, dry, not invested with an involucre. 



Smoothish, globose, about in. in diameter, in cymes with leaf -like bract 



attached 3. TILIA AMERICANA. 



Rough, with scale-like points, ovate, coriacious. .114. PLANERA AQUATICA. 



