16 KEY, BASED UPON FEUIT. 



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 (subgenus Leucobalanus), cup 

 /. About enveloping the small, ovoid nut ; scales thin and appressed. 



68. Q. MUHLENBERGII. 



/ 2 . About enveloping the nut 



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



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



Thinner, edges flaring out after shedding the nut, scales thinnish ; 



peduncles shorter than petioles 67. Q. PRINUS. 



f z . Scarcely enveloping the oblong-ovoid nut about If in. in length. 



116. QUERCUS MICHAUXII. 

 / 4 . About I or more enveloping the nut ; peduncles 



g. Longer than the petioles ; nut in. long, light-brown. 



66. QUERCUS BICOLOR. 



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



f 5 . About \ or more enveloping the nut ; peduncles 



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



g-. 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 2 . On wood of the preceding season (subgenus Melanobalanus); cup 

 /. Saucer-shaped, very shallow, f enveloping the nut. 



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



gr 2 . Flattened-globose; leaves 

 Sinuate-pinnatified. 

 Sin uate-pinnatifid with wide sinuses .... 94. QUERCUS PALUSTRIS. 



Obovate-spatulate, entire 118. QUERCUS AQUATICA. 



/ 2 . Top-shaped, enveloping the acorn ; scales thin and coarse 



Inner bark of tree reddish 69. Q. COCCINEA. 



Inner bark yellowish 93. Q. TINCTORIA. 



<Z 2 . Club-shaped, short, surrounded with stiff hairs, tipped with the persistent 

 recurved style and arranged in globular heads. 



13. PLATANUS OCCIDENTALTS. 

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



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



41. OSTRTA 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. 

 C 8 . Pod (legume) which is 



Oblong, flat, about 2 in. broad and curved. 



27. GYMNOCLADUS CANADENSIS. 

 Linear, twisted and contorted, about 1 in. broad. 



28. GLEDITSCHIA TRIACANTHOS. 

 Obliquely ovate (1-2 in. long), long stalked and mostly 1-seeded. 



109. GLEDITSCHIA MONOSPERMA. 



