Proceedings of the Ohio State Academy of Science 89 



y2. Pith 5-angled ; stipules none, base of petiole with nu- 

 merous vascular bundles, scattered or in 3 areas. 



Hicoria. (15). 



y2. Pith cylindrical or nearly so ; leaves with stipules ; 

 vascular bundles in base of petiole 3-5. Sorbus. (36). 



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

 usually with prominent thorns. Gleditsia. (45). 



73. Pith very large, base of petiole not covering the axillary 



buds; without thorns. Gymnocladus. (46). 



—74— 



74. Leaves simple. yS. 



74. Leaves compound. 75. 



75. Leaves digitate with 5 or more leaflets. Aesculus. (58). 



75. Leaves trifoliate or pinnate. 76. 



y6. Base of petiole covering the axillary buds ; leaflets 

 dentate, lobed, or nearly entire. Acer. (57). 



76. Base of petiole not covering the axillary buds. yy. 



yy. Leaves trifoliate; bark with strong odor; terminal bud 



self-pruned. Staphylea. (56). 

 yy. Leaflets 5-13; terminal bud present. Fraxinus. (69). 

 78. Leaves pinnately veined. 82. 



78. Leaves palmately veined or at least with 2 prominent 



side ribs from the base. 79. 



79. Leaves entire or if somewhat 3-lobed with entire 



margin. 80. 



79. Leaves serrate, crenate, dentate or variously lobed. 81. 



80. Pith diaphragmed, or with large cavities ; petioles usually 



hollow; axillary buds superposed. Paulownia. (72). 



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



under side of leaves with glands in the axils of the 

 larger veins. Catalpa. (73). 



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



Acer. (57). 



81. Leaves not lobed; fruit a drupe. Rhamnus. (60). 



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

 82. Leaves entire. 85. 



