1910.] NATURAL SCIENCES OF PHILADELPHIA. 549 



bieknellii, Lilium philadelphicum , Quercus Uicifolia, Arenaria stricta, 

 and Galium boreale. Of these Sporobolus heterolepis, Deschampsia 

 ccespitosa, Carex bieknellii and Galium boreale here reach their most 

 southerly recorded stations in the Eastern States. 



The species in this district restricted to the Conowingo Barrens are 

 Panicum annulum, Sporobolus heterolepis, Sphenopholis obtusata 

 pubescens, Deschampsia ccespitosa, Atheropogon curtipendulus, Fim- 

 bristylis laxa, Carex bieknellii, Quercus marylandica, Talinum tereti- 

 folium, Cerastium oblongifolium, Arenaria stricta, Asclepias verticillata , 

 Phlox subidata, Scutellaria parvula ambigua, Gerardia purpurea par- 

 vula, and Aster parviceps pusillus. Of these most are wide-ranging 

 and have been considered. 



Of those remaining, Panicum annulum, Sphenopholis obtusata 

 pubescens, and Scutellaria parvula ambigua seem very local here and 

 occur in areas widely remote over most of the Eastern States. 

 Talinum teretifolium, Cerastium oblongifolium and Aster parviceps 

 pusillus in the East, at least, are practically confined to magnesian 

 (i.e., Serpentine) soil. Aster parviceps pusillus, common here, is only 

 known from the Serpentine Barrens of a small area in southern Penn- 

 sylvania and adjacent West Virginia. Cerastium oblongifolium and 

 Talinum teretifolium range west to Minnesota and Colorado / and 

 toward the western part of their range are adapted to other xero- 

 phytic habitats. The range of Gerardia purpurea parvula is not as 

 yet understood. 



I. List of Species Composing the Flora of the Conowingo 



Barrens. 



* Nearly or quite restricted in Delaware and Chester Counties to 



Conowingo Barrens, 

 t Common to surrounding country, but much more frequent on 



Conowingo Barrens. 

 \ Frequent on Conowingo Barrens, but much less common than in 



surrounding district. 

 — Those species of the surrounding flora found as mere stragglers 



on the Conowingo Barrens, also noteworthy introduced species 



are listed at the end. 

 Unless otherwise credited, all records are represented by specimens 



of the writer's collecting. 



fl. OSMUNDA SPECTABILIS L. 



Frequent in rich shaded swamps. 

 Delaware. — Williamson. 



