ANALYTICAL KEY TO THE FAMILIES XXI 



Leaves obtuse or acute. 

 Branchlets not spinescent. 



Leaves glabrous at maturity, their petioles slender. 



Cotinus in Anacardiaceas (p. 601). 

 Leaves pubescent below at maturity ; their petioles short and thick. 



Diospyros Texana in Ebenaceae (p. 750). 

 Branchlets spinescent ; leaves often fascicled on lateral branchlets. 



Bumelia in Sapotaceae (p. 740). 

 cc Leaves linear, fascicled and scattered on the young branches, or 2-ranked in 

 Taxodium. Larix and Taxodium in Coniferae (pp. 34, 70). 



aa Leaves serrate or pinnately lobed. 

 d Stipules present. 

 e Winter-buds naked. 



Leaves oblique at the base, the upper side rounded or subcordate, ob- 

 ovate, coarsely toothed. 



Hamamelis in Hamamelidaceae (p. 341). 

 Leaves equal at the base, cuneate, finely serrate or crenate. 



Rhamnus Caroliniana and Rhamnus Purshiana in 



Rhamnaceae (pp. 663, 664). 

 ee Winter-buds covered by scales. 



Winter-buds with a single pair of connate scales. 



Primary veins arching and uniting within the margins ; leaves sim- 

 ply serrate or crenate, sometiraies entire. 



Salix in Salicaceae (p. 166). 

 Primary veins extending to the teeth, leaves doubly serrate, often 

 slightly lobed. Alnus in Betulaceae (p. 208). 



eee Winter-buds with several pairs of imbricate scales. 



Terminal buds wanting, branchlets prolonged by upper axillary buds. 

 Leaves distinctly oblique at the base. Ulmaceae (p. 287). 



Leaves slightly or not at all oblique at the base. 



Carpinus, Ostrya, and Betula in Betulaceae (pp. 180, 



191, 194). 

 Terminal buds present. 



Primary veins arching and uniting within the margin {extending to 

 the margin in the lobed leaves of Malus). 



Winter-buds resinous ; leaves crenate, usually truncate at the 

 base ; petioles slender. 



Populus in Salicaceae (p. 152). 

 Winter-buds not resinous. 



Malus, Amelanchier, Prunus in Rosaceae (pp. ,351, 



360, 509). 

 Primary veins extending to the teeth or to the lobes. 



Leaves lobed or remotely dentate or crenate ; lobes not serrate, 

 but occasionally coarsely toothed. 



Fagus, Castanea, Quercus in Fagaceae (pp. 217, 



219, 226). 

 Leaves doubly or simply serrate, or lobed, with serrate lobes ; 

 branches often furnished with spines. 



Malus and Crataegus in Rosaceae (pp. 351, 363). 

 dd Stipules wanting, 

 y* Leaves not lobed. 



Leaves subcoriaceous. 

 Leaves obovate, acute. 



Gordonia Altamaha in Theaceae (p. 679). 



