The Trees of Vermont 149 



SUMMER KEY TO THE SPECIES OF PRUNUS 



a. Leaves oblong-ovate to obovate, abruptly acuminate at- the apex ; 

 marginal teeth not incurved. 



b. Margin of leaves sharp-serrate with spreading teeth; leaves not 

 rugose, the veins not prominent ; fruit j4-/^ inch long, bright 

 red, racemose, July-August ; bark of trunk brown, smooth or 

 only slightly fissured ; usually a large shrub, 



P. virginiana, p. 153. 



bb. Margin of leaves crenate-serrate ; leaves more or less rugose, the 



veins prominent ; fruit about 1 inch long, orange-red, clustered, 



August-September ; bark of trunk gray-brown, early splitting off 



in large, thick plates ; a small tree P. nigra, p. 157. 



aa. Leaves oval to oblong-lanceolate, taper-pointed at the apex ; mar- 

 ginal teeth incurved. 



b. Fruit light red, clustered, July-August; twigs usually less than 



),{q inch thick; pith of twigs brown. . . P. pennsylvanica, p. 155. 



bb. Fruit black, racemose, August-September; twigs usually more 



than YiQ inch thick; pith of twigs white. . .P. serotina, p. 151. 



WINTER KEY TO THE SPECIES OF PRUNUS 



a. Terminal bud present ; bark of young trunks rather smooth. 



b. Buds clustered at the tips of all shoots ; twigs usually less than 

 YiQ inch thick; pith of twigs brown. .P. pennsylvanica, p. 155. 

 bb. Buds not clustered, or clustered only on short, spur-like branch- 

 lets ; twigs usually more than Y-^q inch thick; pith of twigs white. 

 c. Buds usually }i inch or less in length; bud-scales uniform in 

 color, apiculate at the apex ; bark on old trunks blackish, rough- 

 scaly ; srnall to large tree P. serotina, p. 151. 



cc. Buds usually ^-^ inch long ; bud-scales grayish on the mar- 

 gins, rounded at the apex ; bark on old trunks brown, smooth 

 or only slightly fissured ; usually a large shrub, 



P. virginiana, p. 153. 



aa. Terminal bud absent; bark of young trunks early splitting off in 



large, thick plates P. nigra, p. 157. 



