PRUNUS NIGRA 189 



than similar varieties in elms, mulberries or haw- 

 thorns, and which no one associates with specific 

 differences. I am not yet prepared to affirm that 

 the wild plum of the North contains but a single 

 species, but I am convinced that no botanist has yet 

 been able to draw designative characters to separate 

 out a second or third species. 



The extreme forms of this Americana plum are 

 so well marked, however, that it will be useful, for 

 purposes of study, if incidental names be given them. 

 I am, therefore, inclined to follow Waugh* in calling 

 this northern type Primus Americana var. nigra. 



It should be said that beyond the Mississippi there 

 is a very pubescent -leaved form of Primus Americana, 

 which is known to botanists as the variety mollisj 

 It is from this type that the Wolf plum comes. 

 There is also a form of this with flowers as com- 

 pletely double as those of St. Peter's Wreath, or 



*F. A. Waugh, Bull. 53, Vt. Exp. Sta. 58 (Aug. 1896): 



P. AMERICANA, Marsh. COMMON WILD PLUM. The type distinguished by 

 entire calyx lobes, which are pubescent on the inner surface ; stone turgid ; 

 leaves oval or slightly obovate ; petioles mostly without glands. Tree spreading, 

 ragged, thorny, 8-20 ft. high ; flowers large, white, on slender pedicels ; leaves 

 very coarsely veined, never glossy or shining ; fruit more or less flattened upon 

 the sides, firm and meaty, the skin tough and glaucous and never glossy, ripening 

 through yellow to red. Occurs wild from New Jersey and New York, to 31 on- 

 tana and Colorada. It varies southward, in Texas and New Mexico represented 

 mostly by the variety mollis. 



Var. NIORA. CANADA PLUM. RED PLUM (P. nigra. Ait ; P. Americana, T. & 

 G. ; and 6th ed. Gray's Manual). In its extreme forms easily distinguished by the 

 glandular-serrate calyx lobes, glabrous on the inner surface ; compressed stone ; 

 broadly oblong-ovate to obovate leaves with petioles bearing two glands. Flowers 

 large, white, with short, thick peduncles conspicuously marked by the scars left 

 by the falling of the bud scales ; pedicels dark red, slender, glabrous ; calyx tube 

 broadly obconic, dark red on the outer and bright red on the inner surface ; fruit 

 oblong-oval, orange-red ; stone nearly oval, compressed. Occurs wild from New- 

 foundland west to Rainy and Assiniboine rivers in Canada, and commonly in the 

 New England states, where it is found alona roadsides and in waste places. 



tThis is Prunus australis of Munson. See Waugh, Hot. Gaz. xxvi., 50. 



