1910.] NATURAL SCIENCES OF PHILADELPHIA. 573 



Serpentine Barrens of southeastern Pennsylvania. 

 Type.— Serpentine, Wawa, Delaware County, Penna., F. W. Pennell 

 2689, coll. Sept. 25, 1910, in Herb. Acad. Nat. Sci. Phila, 

 Locally frequent in depressions, or edges of woodland. 

 Delawa re. — Wawa . 



Chester.— Sugartown Barrens; Serpentine Ridge; Cedar Barrens. 

 — Nottingham Barrens. 



$175. Gerardia tenuifolia Vahl. 

 Frequent in diy border-woodland. 

 Delaware. — Fawkes Run. 

 Chester. — Sugartown Barrens. 



176. HOUSTONIA CCERULEA L. 



Common on dry to moist open barren. 

 Delaware. — Mineral Hill; Williamson; Wawa. 

 Chester. — Cedar Barrens; West Chester; Unionville. 



$177. MlTCHELLA REPENS L. 



Frequent in dry border-woodland. 

 Delaware. — Middletown Barrens. 

 Chester. — Sugartown Barrens. 



178. Galium pilosum Ait. 

 Frequent on dry open barren. 

 Delaware. — Mineral Hill. 

 Chester. — Sugartown Barrens ; West Chester ; Unionville. 



f-179. Galium bore ale L. 

 Along border and in greenbrier thicket on State-line Barrens. 

 Chester. — Nottingham Barrens. 



180. Lonicera sempervirens L. 

 Occasional in greenbrier thicket. 

 Chester. — Cedar Barrens (A. Jahn). 



181. Lobelia spicata Lam. 

 Common on dry open barren. 



Delaware. — Bear Hill; Blue Hill; Williamson; Wawa. 

 Chester. — Sugartown Barrens; Serpentine Ridge; Cedar Barrens; 

 West Chester; Brinton's Quarry; Unionville. 



182. Hieragium venosum L. 

 Frequent in dry woodland. 



