1920.] NATURAL SCIENCES OF PHILADELPHIA. 99 



Monotropa uniflora L. 



Habitat. — Dry and occasionally moist upland peat. 



Acidity. — ■ 



5+ X • 



4 



3 



2 X 



1 X 



300 100 30 10 3 1 



The optimum soil reaction of this species is subacid; its range is 



apparently rather more limited than those of preceding members of 



the Ericaceae. The most acid reaction was noted in sandy upland 



peat in southern Delaware; the least acid in clayey upland peat 



at two widely separated localities near Washington, D. C. 



Hypopitys lanuginosa (Miclix.) Nuttall 



Habitat. — Dry and occasionally moist upland peat. 



Tests have been made on Hypopitys chiefly during the winter, 

 and the species could not be accurately determined. Plants ap- 

 proaching H. lanuginosa in characters have been examined at two 

 localities near Washington, D. C, in clayey upland peat, and yielded 

 subacid reaction in both cases. 



Hsrpopitys americana (De Candolle) Small. 



, Habitat. — Dry upland peat. 



Plants probably referable to H. americana have been examined 

 near Dover, N. J., the soil being sandy upland peat over glacial 

 drift, and the reaction subacid. 



Azalea nudiflora L. 



Habitat. — Dry upland peat and occasionally wet sphagnum peat. 



Acidity. — 



5+ X 



4 X 



3 



2 



1 X X X 



300 100 30 10 3 1 



The optimum soil reaction of this species is subacid. The most 

 acid reaction tabulated was observed in a swamp in southern Dela- 

 ware; the least acid in upland peat over calcareous glacial drift 

 near Green Pond, N. J. 



Azalea canescens D. Don. 



Habitat. — Dry upland peat. 



This species has been observed but rarely, in the mountains of 

 central Pennsylvania; the soil in these cases is upland peat over 

 sandstone rocks, and the reaction subacid or rarely mediacid. 



