ROSACEAE. 



127 



PEUNUS. 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 flanked 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. 



