1 8 A Bud and Twig Key 



f2. Bud globular very small, three scales visible, a 

 one-fourth inch thorn accompanying the axil- 

 lary bud, leaf -scar small round with one bun- 

 dle-scar or several clustered in the center, stip- 

 ule-scars very small, twigs small, sap milky, 

 pith of the older branchlets often yellow, no 

 terminal bud, tip-scar indistinct. 



Toxylon pomiferum Raf. 



/j. Buds ovate or long oval, apex acute, two to 

 four scales visible. 



gi. Bundle-scars three, dwarf shoots common, 

 buds long oval about one-fourth inch long, 

 twigs small, no terminal bud, tip-scar dis- 

 tinct. * Betula Linn. 



hi. Twigs dull red, becoming shiny dark yel- 

 lowish brown the second year, buds slight- 

 ly resinous. Plate V. 



B. papyrifera Marsh. 



Ji2. Twigs light yellowish brown, becoming 

 shiny yellowish brown. 



B. lute a Michx. 



7ij. Twigs very dark red shiny becoming dull 

 reddish brown the second year. 



B. nigra Linn. 



hf. Twigs bright red brow r n shiny becoming 

 dull brown, have wintergreen flavor. 



B. lent a Linn. 



gs. Bundle-scars four to six or more scattered, 

 no dwarf shoots, stipule-scars small but 

 distinct, no terminal bud, tip-scar distinct. 

 hi. Pith five-angled, buds glabrous dark brown 

 ovate or oval scarcely one-fourth inch 

 long, twig glabrous brown. 



Castanea dcntata (Marsh.) Borkh. 



* Distinction between the species is difficult from twigs alone. 



