ROSACEAE. 127 
Prunus. Plum, Cherry, etc. 
(Family Rosaceae). 
Shrubs or trees: deciduous, or 
the cherry laurels evergreen. 
Twigs slender or moderate, sub- 
terete or somewhat angled from 
the nodes, occasionally spine- 
tipped: pith roundish or angled, 
pale or brown, continuous. Buds 
solitary or collaterally multiple, 
sessile, subglobose or mostly ovoid, 
with usually a half-dozen ex- 
posed scales, the end-bud lacking 
in certain groups (apricots, 
plums). Leaf-scars alternate, 
raised on a cushion fianked by 
the stipule vestiges or scars, half- 
round or  half-elliptical, small: 
bundle-traces 3, usually minute. 
Leaves of the evergreens are 
simple, mostly entire, and with 
round nectar-disks on the back. 
Like Pyrus, this genus is con- 
fusingly complex through inclusion of such diverse forms as 
the evergreen cherry-laurels and the deciduous types repre- 
sented by peach, apricot, plum, cherry and bird-cherry, which 
nevertheless do not segregate by characters satisfactory to 
many botanists. 
Though the different cherries are sufficiently distinct 
from one another, the American plums are almost as trouble- 
some as the red haws. Only the most distinct of their types 
are differentiated in the key here given. 
A classified bibliography of Prunus is given by Rehder in 
volume three of the Bradley Bibliography, compiled by him 
at the Arnold Arboretum. 
6 A ‘ , 
Ly 
