PRUNUS 



163 



Prunus Linne 1753 



(Classical L. name of the plum-tree) 



Trees or shrubs, sometimes spiny ; leaves alternate, simple and serrate ; 

 flowers variously clustered, white or pink; calyx tube campanulate or 

 obconic, sepals 5, petals 5, spreading; stamens 15-20, distinct, filaments 

 slender; pistil 1, in the hollow cup-shaped calyx tube, style terminal; 

 ovule 1 ; fruit a drupe, stone smooth or a little roughened, globose or oval, 

 or oblong and flattened. 



A genus of 90 species, natives of the north temperate zone, tropical 

 America and Asia. In addition to the following about 25 species occur 

 in North America. 



Key to the Species. 



1. Flowers single Cherries and Plums 



a. Large shrubs or trees 



( 1 ) Flowers in racemes, terminating the sea- 



son's growth 



(a) Small tree, or large shrub, leaves 



broadly ovate P. virginiana 



(b) Large tree, leaves narrowly ovate or 



lanceolate P. serotina 



(2) Flowers in scaly umbels or corymbs, ex- 



panding with or before the leaves 



(a) Branches usually thorny or armed, 



fruit sub-globose, borne singly 



Plums 

 x. Teeth of leaves obtuse, gland-tipped, 



stone of fruit flat 

 y. Teeth of leaves acute, bristle-tipped, 



stone round 



(b) Branches not thorny or armed, fruit 



globose or sub-globose Cherries 

 x. Flowers in corymbs, small, petals 4-6 



mm. long, fruit 3-6 mm. 

 y. Flowers in umbels, large, petals 8-12 



mm. long, fruit 8-15 mm. 



b. Dwarf shrubs, (1-4 ft.), with narrow leaves 



(1) Shrub with wand-like branches, leaves 



thin P. 



(2) Bushy shrub, leaves thick P. 



P. nigra 



P. americana 



P. pennsylvanica 



P. cerasus 



pumila 

 Besseyi 



