THE PLUMS OK NEW YORK. 43 



dens in Europe and somewhat in America. Its blossoms arc pure white, 

 about half an inch in diameter and not quite double, as the stamens form 

 an orange cluster in the center of the flower. The flowers are thickly 

 crowded on short spiny branches, the dark color of which forms a striking 

 contrast to the white flower. Primus spinosa purpurea is another horti- 

 cultural group, more vigorous than the species, less thorny and with larger 

 foliage. Its branches are erect, purplish in color, striated. The leaves 

 and petioles are at first very pubescent but at maturity glabrous; the 

 upper surface of the leaf is green marked with red, the under a deep red- 

 dish-violet. The flowers are a pale rose. One or two variegated forms 

 of this species are also offered by nurserymen. 



Schneider holds ' Prunus jruticans Weihe' and Primus spinosa mac- 

 rocarpa Wallroth' to be crosses between Prunus spinosa and Prunus 

 insititia. 



Prunus spinosa, the Blackthorn or European Sloe, is the common 

 wild plum of temperate Evirope and the adjoining parts of Asia. It is 

 adventive from Europe to America and is now quite naturalized along 

 roadsides and about fields in many places in eastern United States. Prunus 

 spinosa is considered by some authors the remote ancestor of the Domestica 

 and Insititia plirnis, but as brought out in the discussion of the last named 

 species, such parentage is very doubtful. 



The Spinosa plum is a common and often pestiferous plant in its 

 habitat, the roots forming such a mass that in general it is impossible 

 for any other vegetation to grow in its vicinity. The plant is small, spread- 

 ing and much branched and bristles with sharp thorns. The leaves are 

 smaller than those of any of the other Old World species, ovate in shape 

 and very finely serrate. The flowers are usually single but sometimes in 

 pairs or threes and are borne in such number as to make a dazzling mass 

 of white; comparatively few of these, however, set fruit. The fruit is 

 round and small, usually less than half an inch in diameter, and, tj-pically, 

 so black as to have given rise to the old saying, " as black as a sloe." 

 The fruits are firm but rather juicy, with an acid, austere flavor, which 

 makes them lonfit for eating out of hand until frost-bitten, when the 

 austereness is somewhat mitigated. The stone is much swollen, with 

 one edge acute. 



' Handb. Laubh. i: 630. 1906. 



2 Flora 9:748.1826. 



^ Sched. Cril. 217. 1822. 



