352 FOREST TREES OF THE PACIFIC SLOPE. 



Flowers of Primus, appearing from buds on twigs of the previous year, either 

 with the leaves, or before or after them, are similar in general appearance 

 to those of the hawthorns, apples, and pears, but different in structural details. 

 They depend for cross-fertilization entirely upon insects. The fruits, more or 

 less juicy and sweet, acid, or very bitter, are matured in one season, either in 

 early or late summer. Luscious in flavor or attractive in appearance, plum and 

 cherry fruits are eaten extensively by birds and mammals (without injury to 

 the seeds) and thus widely disseminated; otherwise these trees depend for dis- 

 tribution of their seeds upon flood waters. The leaves are arranged on the 

 twigs as in the apples and haws, and are either shed every autumn or, in some 

 species, are evergreen. 



Sixteen species of Primus occur iu the United States and adjacent territory, 

 4 of which inhabit the Pacific region. 



Western Plum. 

 Prunus subcordata Bentham. 



DISTINGUISHING CHARACTERISTICS. 



The name " western plum." suggested here, is not the field name of this tree, 

 which is " plum " or " wild plum," indefinite names which are applied also to 

 several eastern wild plum-trees. To avoid confusion, it is hoped " western 

 plum " will be used. 



Generally a stocky, crooked-stemmed shrub from 2 to 10 feet high in dry 

 situations, but in moist, rich soils a tree from 15 to 20 feet high and from 4 to 

 C> inches (sometimes more) in diameter. The short, clear trunk, ashy brown, 

 seamed, and scaly, gives off thick limbs, which stand out nearly at right angles 

 to the stem, and have many short, stubby twigs, some of which are spine-like. 

 Season's twigs are clear red to deep purple-red, usually smooth (sometimes 

 minutely hairy), with sharp-pointed red buds. Mature leaves (fig. 165), shed in 

 autumn, are commonly smooth on their top sides but very often minutely hairy, 

 as they always are beneath ; about 1} to nearly 3 inches iu length ; in dying 

 they become bright red and yellow. The white flowers appear before the leaves 

 in early spring. Mature fruit (fig. 165), ripe in early autumn, is deep purple- 

 red, three-fourths inch to about 1 inch long, with a pointed flat stone, which 

 has a conspicuous, thin, keel-like edge on one side only, the opposite side being 

 grooved. The flesh of the fruit is edible and much used locally, is juicy and 

 somewhat tart : variable in quality. 



Wood, fine-grained, very dull light brown, with thin sapwood ; of no eco- 

 nomic use. 



With other chaparral the tree sometimes forms good protective slope cover 

 on dry slopes. 



Longevity. — Not fully determined. A tree Gi inches in diameter showed an 

 age of 48 years. Probably short-lived. 



A variety of this plum. Primus subcordata kelloggii Leminon, is distinguished 

 by its yellow sweet fruit and in its nearly smooth foliage ; especially abundant 

 in Shasta and Sierra counties. Yellow fruited forms of other wild plums and 

 of cherries are known. 



Southern Oregon to central California (west of the Cascades and Sierra Madre Moun- 

 tains). 



