Proceedings of the Ohio State Academy of Science 99 



resinous or if only slightly so then the twigs pubescent 

 or tomentose. Populus. (ii). 

 6i. Pith very large, light brown, bark not resinous, ill- 

 smelling; buds spherical or flattened at the apex, 

 often clustered at the tip of the twig, brown and pubes- 

 cent ; bundle scars about 9 along the lower edge of 

 the very large leaf scar ; large trees. Ailanthus. (51). 



61. Pith small, or if large and brown then the bark 



resinous. 62. 



62. Bark with a resinous or sticky milky sap ; pith usually 



large, if rather small then the bark aromatic. 63. 



62. Bark not resinous. 64. 



63. Buds clustered at the tip of the twig ; bark spicy-fragrant 



to the smell ; base of petiole prominent with several 

 bundle scars ; fruiting panicles plumose. 



Cotinus. (53). 



63. Buds not clustered at the tip ; bark sometimes aromatic, 



often very poisonous to the touch ; leaf scar partly 

 surrounding the bud or the bud covered ; small trees 

 or shrubs. Rhus. (52). 



64. Terminal bud absent. 65. 



64. Terminal bud present. 68. 



65. Stipules or stipular scars absent or indistinct. 66. 



65. Stipules or stipular scars present. 67. 



66. Buds clustered at the tip of the twig; young twigs 



glandular dotted. Myrica. (13). 



66. Buds not clustered at the tip ; twigs not glandular. 



Prunus. (42). 



67. Buds and twigs very down}-, twigs dark brown or black. 



Cydonia. (39). 



67. Buds downy or pubescent ; twigs glabrous or pubescent, 



gray or brown. Rhamnus. (60). 



68. Twigs green or yellowish-green, glabrous ; internodes 



very unequal ; lateral buds minute ; small trees. 



Comus. (75). 

 68. Twigs normally red above and green beneath, glabrous ; 



