548 PROCEEDINGS OF THE ACADEMY OF [Oct., 



Many other notable species occur irregularly or in but one or t\\ o 

 areas. Of commoner species Phlox subulata is a conspicuous instance. 

 Of scarcer species may be mentioned Pinus virginiana, Ari&tida 

 oligantha, Sphcnopholis obtusata pubescens, Aletris farinosa. Meihomia 

 rigida, Sarothra gentianoides, Viola pedata lineariloba, Gentiana crinita, 

 Phlox pilosa, Scutellaria pamila airibigua, Gerard ia purpurea parvula, 

 Castilleia coccinea, Lonicera semperrirens, Lacinaria spicata, Aster 

 patens and Antennaria neodioica. 



Geographical Affinities of the Flora. 



The following list shows 217 species composing the characteristic 

 flora of the Conowingo Barrens, while some 77 others were collected 

 occasionally. Of the characteristic species 17 in this section of the 

 Piedmont area are quite or nearly confined to these barrens, while 

 4 s others occur mainly here. The remaining- species belong to the 

 normal flora of the district, and their distribution will be less considered. 



-Many of the species occurring mainly on the Conowingo Barrens 

 occur also on other barren (xerophytic) formations of the district, 

 as the South Valley Hill (shale) and the North Valley Hill (quartzite 

 and sandstone). Among such may be mentioned Panicum philadel- 

 phicum, P. depaupcratum, P. scribnerianum, P. sphwrocarpon, Aristida 

 gracilis, Juncus secundus, Smilax glauca, S. rotundifolia, Sisyrinchium 

 mucronaium, Quereus dieifolia, Q. stellata. Q. prinoides, Comandra 

 umbellata, Polygonutn tenue, Lespedeza capitata, L. virginica, Angelica 

 villosa, and Senecio balsamitce. A common dry light soil accounts 

 for such distribution. 



Across the Delaware River in New Jersey, also in southern Delaware, 

 lie the sand barrens of the Atlantic Coastal Plain. From here have 

 evidently been derived a number of coastal (Carolinian) species. 

 Besides all the above list of xerophytes, Pinus virginiana, P. rigida, 

 Aristida oligantha, A. purpurascens, Scleria triglomerata , Quereus 

 marylandica, Cassia chamarrista, Strophostyles umbelleda, Asclepias 

 verticillata, Phlox subidata, Eupatorium aromaticum are species present 

 to both floras. Other less characteristic species showing coastal 

 influence are Typha angustifolia, Panicum commonsianum, P. addisonii, 

 Juncus aristulatus, Aletris farinosa and Pieris mariana. Fimbristylis 

 laxa. though not found in New Jersey, likewise seems to imply a coast- 

 ward southern influence. 



Distinctive species in the characteristic Conowingo flora showing 

 a northern or Alleghanian influence are Sporobolus heterolepis, Des- 

 chaynpsia ca'spitosa. Atheropogon cvrtipendulus, Carex glaucodea, C. 



