22 BULLETIISr 179, U. S. DEPAKTMEISTT OF AGEICULTTJRE. 



ripening from the second week in August to the end of September; 

 stone (PL IX, figs. 1 to 7) oblong-oval, rather flat, about 20 mm. long, 

 14 mm. broad, obUquely truncate at the base and rounded at the 

 apex, grooved on either side a short distance from the ventral edge, 

 and with a single groove along the dorsal edge. 



Prunus nigra is a small tree, attaining a maximum height of about 

 30 feet. It sprouts from the roots and frequently forms small thick- 

 ets. The grayish bark of the trunk exfohates in platehke scales, 

 while that of the young twigs is smoother and very dark gray. The 

 branches are often furnished with spinescent branchlets, and the 

 winter buds are lanceolate in outline, acute, and 4 to 5 mm. long. 

 The wood is heavy, close grained, and strong. 



While Prunus nigra has often been confused with P. americana, 

 it is nevertheless one of the most distinct and easUy recognizable of 

 the native species. The fohage is distinguished from the latter spe- 

 cies by the rounded instead of pointed serrations of the leaves. The 

 flowers are larger, have a more pinkish tinge when fading, and appear 

 earher in the same locahty; the calyx lobes are glandular serrate and 

 usually glabrous, while in P. americana they are inconspicuously 

 glandular or eglandular and pubescent within. 



Prunus nigra^ grows (fig. 1) in the alluvial valleys of streams or 

 often on limestone hiUs, and ranges from the vicinity of the St. John 

 Kiver in western New Brunswick through Maine, excepting the 

 extreme northern portion, to the valley of the St. Lawrence and west- 

 ward to the southern shores of Georgian Bay and nearly to the shores 

 of Lake Michigan in the southern peninsula of the State of Michigan. 

 It extends southward to central Massachusetts, though probably as 

 an introduced plant in that State, but occurs apparently as a native 

 at Ithaca, N. Y., and in northern Ohio near the Black River, in 

 Lorain County; thence its Hne of southern distribution moves north- 

 ward to the vicinity of Lake St. Clair, Lansing, and Grand Rapids, 

 Mich. It does not occur in the sandy soils of the lake region of west- 

 ern Mchigan, but reappears in northeastern Illinois, extending from 

 near Johet to the southern part of Dodge County and the vicinity of 

 Milwaukee, in southeastern Wisconsm. It does not appear to have 

 been observed in central Wisconsin, but is found in the western part 

 of the State, where it extends northward from the vicinity of the 

 Wisconsin River and through eastern Minnesota to the region west 

 of Port Arthur, in western Ontario, and to the Winnipeg Valley, 

 where it was collected by Bourgeau in 1857. 



1 Although this species is reported by Hooker (33, p. 168) from Newfoundland, Dr. M. L. Femald, who 

 has collected extensirely ia New Brunswick and Newfoundland, writes that he has no knowledge of it east 

 of the St. John River system. He says: ' 'It is fahly abundant on terraces and limey slopes near the mouth 

 of the Aroostook River, which is its northeastern limit, I think." The herbarium material examined con- 

 firms this view of the northeastern limit of the species. 



