i. Leaf-lobes coarsely sinuate-toothed 



PLATANUS, p. 141. 



ii. Leaf-lobes serrate. 



j. Branches armed with stiff, sharp thorns; 



sap not milky CRATAEGUS, p. 151. 



jj. Branches unarmed ; sap milky 



MORUS, p.j3S. 



cc. Leaves opposite or whorled. 



d. Margin of leaves entire or only slightly undulate, 

 e. Leaves 3-5 inches long; spray fine; fruit an ovoid 1 , 



scarlet drupe CORNUS, p. 202. 



ee. Leaves 5-12 inches long; spray coarse; fruit a long, 



slender-cylindrical capsule CATALPA, p. 222. 



dd. Margin of leaves serrate to lobed. 



e. Margin of leaves finely serrate 



VIBURNUM, p. 229. 



ee. Margin of leaves distinctly lobed ACER, p. 172. 



aa. Leaves compound, 

 b. Leaves alternate, 

 c. Leaves simple-pinnate. 



d. Branchlets armed with short, sharp prickles 



ROBINIA, p. 169. 



dd. Branchlets unarmed. 



e. Leaflets entire with the exception of 2 or more 



coarse, glandular teeth at the base 



AILANTHUS, p. 171. 



ee. Leaflets serrate the entire length. 



f. Upper leaflets less than i inch broad, 

 g. Trunk and large branches armed with stout 



spines: leaflets ^-I 1 A inches long 



GLEDITSIA, p. 165. 



gg. Trunk and large branches unarmed; leaflets 2-3 



inches long PYRUS, p. 142. 



ff. Upper leaflets 1-5 inches broad. 



g. Leaflets 5-1.1 ; pith homogeneous 



GARY A, p. 66. 



gg. Leaflets 11-23; pith chambered , 



JUGLANS, p. 60. 



cc. Leaves bi-pinnate. 



xxv 



