172 Rhodora | , [OCTOBER 
this station for the cherry consisted of comparatively few individuals 
in1905. There are now some scores of trees of various ages thoroughly 
naturalized on the wooded slopes and especially along the streamlet 
in the alluvial bottom. They appear quite as indigenous to the 
gully as the associated Spice Bush, Slippery Elm, and other native 
shrubs and trees characteristic of southeastern Pennsylvania. In 
spring the alluvium of this gully, however, is carpeted with the Lesser 
Celandine. The Japanese Knotweed has become well naturalized 
here, and nearby is an extensive colony of Goutweed. The site of 
the old Pennock greenhouses is not far away; possibly the origin of 
some of these plants is to be traced to the Pennock place. Small 
. dwellings are now being built along the slopes and a road has been 
run diagonally down and across the gully, but the wooded character 
of the locality is apparently being carefully preserved and the cherry 
in large measure may remain undisturbed. 
More than twenty years ago the late Alexander MacElwee collected 
the Bird Cherry in the northwestern part of Philadelphia, along Gor- 
gas Lane in Germantown. In 1921 there was an opportunity with 
Mr. MacElwee's assistance to re-explore this region, which is near 
the head of Wingohocking Creek. He selected a position along the 
Philadelphia and Reading Railway just northwest of where Washington 
Lane Station is now located as probably the spot where he made 
his collection in 1899. Here, escaped the processes of "improve- 
ment," are still remnants of natural woodland, now, however, filled 
up solidly in many places with the Empress Tree and the Gray 
Birch (a naturalized species here),! as well as with an equally weedy 
growth of the Wild Black Cherry. Seedlings of the Bird Cherry, 
and young trees up to six or seven feet high, may be found scattered 
through the woodlands for at least a quarter-mile. Near a pictur- 
esque, ruined old springhouse in these woods is a thirty-foot tree of 
the Bird Cherry. The large size and the proximity to the springhouse 
suggest the possibility of its being a relic of cultivation and the * moth- 
er tree” of the Bird Cherries in this vicinity. 
1 The discriminating botanist familiar in the field with the local flora of southeastern ` 
Pennsylvania and southern New Jersey recognizes that Betula populifolia, as a native 
tree, is almost absent from the lower Piedmont area. It is common on the Coastal 
Plain but above the fall line reappears as a definitely indigenous and characteristic 
species only at the foot of the Alleghanies. In this wide intervening stretch of 
country most of the few occurrences known can be shown to be cases of introduction. 
1t has a strong tendency to become a weed on filled ground or on disturbed, parti- 
cularly clayey soils. 
