18 KEY, BASED UPON FKUIT. 



e 9 . 4 more or less distinct valves (Carya). 

 f. Epicarp thick and separating quite freely to the base; nut ridged with 



thick shell, globular-ovoid and 

 g. Flattened. 



1 in. or less in length , 36. CARYA ALBA. 



1 in. or more in length 64. CARYA SULCATA. 



gr. 9 Not so much flattened, usually 4 angled. 



90. CARYA TOMENTOSA. 



/. Epicarp only moderately thick and nut of medium size, moderately 

 ridged and with shell of medium thickness. 



65. CARYA PORCINA. 

 / a , Epicarp thin, nuts small and thin-shelled; kernel 



g. Astringent and bitter; sutures of epicarp very prominent; nut 

 Quite smooth, whitish and only slighly compressed. 



37. CARYA AMARA. 

 Rough, reddish, strongly compressed and angled. 



115. CARYA AQUATICA. 



gr 2 . Slightly if at all bitter, nut whitish and sutures moderately promi- 

 nent 91. CARYA MICROCARPA. 



d.* Covered with spines ; dehiscent 

 e. By four valves; nuts 



Sharply 3-angled, 2 together, involucre soft-prickly. 



16. FAGUS FERRUGTNEA. 



Subovoid, flattened, 1-3 together, involucral spines very sharp and hard. 



40. CASTANEA VESCA. 

 e.* Irregularly; spines many-branched; nut maturing the second year. 



139. CASTANOPSIS CHRYSOPHYLLA. 

 C. 9 Small, ovoid-laneeolate pods arranged in catkins, opening by two valves and 



containing numerous seeds furnished with silky down; leaves 

 d. Orbicular-ovate ; petioles flattened; leaves 



Dentate 18. POPULUS GRANDIDENTATA. 



Finely serrate, sharply pointed 72. P. TREMULOIDES. 



Sinuate-toothed, tomentose beneath 96. P. ALBA. 



Obscurely-serrate, with obtuse or rounded apex. 97. P. HETEROPHYLLA. 

 d.* Ovate, closely serrate, whitish and reticulate- veined beneath. 



47. P. BALSAMIFERA. 



d. 3 Deltoid-ovate 48. P. MONILIFERA. 



d. 4 Broadly deltoid 73. P. DILATATA. 



d. 6 Linear-lanceolate, tomentose on midrib above and petiole. 



45. SALIX NIGRA 

 d.* Lanceolate or elliptic-lanceolate, smooth above; capsules 



e. Sessile or nearly so 46. SALIX ALBA var. VITELLINA. 



e. 9 With slender pedicels; leaves 



2-4 in. long 71. .SALIX AMYGDALOIDES. 



3-7 in. long 140. SALIX LAEVIGATA. 



C*. Linear compressed pods, opening by two valves. 



80. ROBINIA PSEUD ACACIA. 

 C 4 . Subcylindrical pods, long, opening by two valves. 



6-10 in. long, \ in. or less thick 134. CHILOPSIS SALIGNA. 



10-12 in. or more long, in. or more thick. ..89. CATALPA BIGNONIOIDES. 



