98 PHYSICAL GEOGRAPHY. 



Americana have oval or obovate leaves (broader at the tip than 

 where the stem is attached), with saw-toothed or doubly saw-toothed 

 edges and very full of veins. The fruit is globular or oval, and 

 ranges from a half-inch to an inch and a quarter in diameter, the 

 latter being an exceptionally large size. The color is all shades of 

 yellow, with some red and crimson. Its juice is pleasant, but its 

 skin is tough and acerb; and its stone is sharp edged or margined. 

 The shrub varies in height from six to twenty-five feet. The fruit 

 ripens in August and the first half of September. These are the 

 prevailing characters, but they vary greatly, some of the varieties 

 producing fruit which is a great imjorovement in size and taste on 

 the type species, while others again have deteriorated. Nearly all 

 the varieties part readily from the stone. 



Still more subject to change is the Prunus chicasa, which grows 

 from four to twelve feet in height, sometimes thorny, and always 

 with long, narrow, almost lance-shaped, acute leaves, whose edges 

 are set with very fine teeth. The fruit is globular, of all shades of 

 red, and from half an inch to an inch or more in diameter, of pleas- 

 ant (some varieties, of delicious) flavor, thin-skinned, and contain- 

 ing an almost round and entirely marginless stone. Most of 

 the varieties of this plum do not part readily from the stone. The 

 fruit ripens the latter part of July and in August. 



I have found many forms that cannot be readily classed with eith- 

 er of these species, but seem to be a cross between the two. In 

 fact these plums often hybridize. This is not strange where both 

 species often grow together in such compact thickets that it is difficult 

 to penetrate them. When the pollen of the one is carried to the pis- 

 tils of the other species the young plants that come from the seeds 

 must exhibit some characters which are common to both. 



One variety of the Prunus A??iericana, that grows from six to ten 

 feet in height, and has greenish white fruit, occasionally tinged with 

 yellow, rarely ripens its fruit. I have seen its fruit hard and green 

 towards the end of October; but when plucked, even then, and 

 stowed away in an empty room, it readily ripens, like pears when 

 similarly treated. Occasionally a tree is found producing a little 

 round red plum, slightly larger than a morella cherry, which bears 

 double fruit. 



Delicious as some of these wild plums are, their size and flavor 

 are much improved by cultivation and pruning. It is easy to pro- 



