208 TREES IN WINTER 



149. Habit erect, generally with a central leader 



^ ^^ Sweet Cherry (Prunus avium) p.368 



149. Habit spreading, without central leader; buds smaller; twigs more 

 slender Sour Cherry (Prunus Cerasus) p.370 



150. Bud-scales gray-margined; buds generally over 5 mm. long; bark 



smooth; generally only a shrub 



Choke Cherry (Prunus virginianaj p.364 



150. Bud-scales uniform in color; buds generally under 5 mm. long; 



bark becoming rough-scaly; a small to large tree 



Wild Black Cherry (Prunus serotinaj p.362 



151. Native species, growing wild 152 



151. Cultivated species. Varieties chiefly of the American, European, 

 or Japanese type of Plum, p.374 



152. Buds generally under 4 mm. long 



American \^^ild Plum (Prunus americana) p.374 



152. Buds generally over 4 mm. long. Canada Plum (Prunus nigra) p.372 



THE SUMACHS 

 Rhus. 



i 



Shrubs or small trees with pithy twigs and milky or watery juice; 

 leaf-scars alternate, more than 2-ranked; bundle-scars numerous scat- 

 tered or in a single curved line; stipule-scars absent; terminal bud 

 present or absent; fruit a small drupe borne on erect or drooping 

 clusters. 



153. Terminal bud present; fruit smooth white in loose drooping clus- 

 ters Poison Sumach (Rhus Vernix) p.394 



153. Terminal bud absent; fruit more or less hairy, red, in dense erect 

 clusters 154 



154. Leaf-scars narrow, V-shaped, nearly encircling the buds; cut twig 

 showing milky juice 155 



154. Leaf-scars broader; inversely triangular to broadly crescent- 

 shaped; twig with watery juice and resinous taste 



Dwarf Sumach (Rhus copallina) under Comparisons p.392 



155. Twigs densely hairy Staghorn Sumach (Rhus typhina) p.392 



155. Twigs smooth 



Smooth Sumach (Rhus glabra) under Comparisons p.392 



THE MAPLES 

 Acer. 



Leaf-scars opposite, narrow U or V-shaped; bundle-scars conspicuous, 

 equidistant, typically 3, though sometimes each of these becomes 

 compounded; fruit winged, in pairs. 



156. Conspicuous, narrow tooth present between leaf-scars 157 



156. Conspicuous tooth absent from between leaf-scars 159 



157. Buds white-downy, collateral buds generally present, twigs gener- 

 ally with a bloom. Box Eliler (Acer Negundo) p.412 



157. Buds smooth, collateral buds never present, twigs without bloom 

 158 



158. Buds with only one pair of scales visible, older branchlets white- 

 streaked Striped Maple (Acer pennsylvanicum) p.398 



158. Buds with several pairs of scales visible, branchlets not white- 

 streaked Norway Maple (Acer platanoides) p.408 



159. Outer single pair of bud-scales equalling the bud in length, their 

 edges meeting and enclosing the bud, therefore generally only 

 one pair of scales visible; pith brown; shrubs or at the most 

 small trees 160 



159. Outer pair of scales shorter than bud, their edges not meeting, 

 therefore several pairs of scales visible; trees 161 



160. Buds and twigs stout, smooth; young bark with longitudinal white 

 lines Striped Maple (Acer pennsylvanicum) p.398 



