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. 135. 



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, 



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. 1/2. 



aa. Leaves comound. 

 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 ^4-1^2 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 5-11; pith homogeneous 



CARYA, p. 66. 



gg. Leaflets 11-23 ; pith chambered 



JUGLANS, p. 60. 



cc. Leaves bi-pinnate. 



xxv 



