20 Field Manual 



7J. I'ith 't-aiigled; stipules none, base of petiole with nu- 

 merous vascular bundles, scattered or in 3 areas. 



Hicoria. (61). 



72. Pith not o-angled; stipules none; leaflets more or less 

 lobed; vascular bundles in base of petiole scattered: 

 terminal bud absent. Koelreuteria. (39). 



72. Pith cylindrical or nearly so; leaves with stipules; 



vascular bundles in base of petiole 3-5. Sorbus. (21). 



73. Pith small; base of petiole covering the axillary buds; 



usually with prominent thorns. Gleditsia. (30). 

 7:». Pith very large, base of petiole not covering the 

 axillar}' buds; without thorns. Gymnocladus. (31) 



—74— 



74. Leaves simple. 78. 



74. Leaves compound. 7-5. 



75. Leaves digitate with 5 or more leaflets. Aesculus. (40). 



75. Leaves trifoliate or pinnate. 76. 



7(1. Base of petiole covering the axillary buds; leaflets 

 dentate, lobed, or nearly entire. Acer. (41-). 



76. Rase of petiole not covering the axillary buds. 77. 



77. Leaves trifoliate; bark with strong odor; terminal 



bud self-pruned. Staphylea. (37). 



77. Leaflets 5-13; terminal bud present. Fraxinus. (74). 



78. Leaves pinnately veined. 82. 



78. Leaves palmately veined or at least with 2 promineiit 



side ribs from the base. 79. 



79. Leaves entire or if somewhat 3-lobe(l with entire 



margin. 80. 

 7!>. Leaves serrate, crenate, dentate or variously lobed. 81. 

 SO. Pith diaphragmed, or with large cavities; petioles 



usually hollow; axillary buds super[)osed. 



Paulownia. (76). 



80. Pith and petioles solid; axillary buds not superposed; 



under side of leaves with glands in the axils of the 

 larger veins. Catalpa. (77). 

 Si. Leaves more or less lobed; fruit a 2-winged samara. 



Acer. (41). 



81. Leaves not lobed; fruit a drupe. Rhamnus. (34). 



82. Leaves serrate, dentate, crenate, or variously lobed. 83. 



