1920.] NATURAL SCIENCES OF PHILADELPHIA. 105 



Gaylussacia brachycera (Michx.) Gray. 



Hahiiat.—Dry upland peat. 



This species has been studied at the two stations known at present, 

 New Bloomfield, Pa., and Millsboro, Del.^^ In both places the 

 dominant soil acidity around its roots is mediacid, ranging to subacid 

 here and there. At the Pennsylvania locality the underlying clayey 

 soil (derived from disintegration of Devonian shale) is lower than 

 this in acidity, being minimacid, but the plant tends to avoid the 

 raw soil, and to grow most profusely wherever vegetable matter is 

 in course of decay. It follows especiall}^ the courses of old fallen 

 tree trunks, (and stumps), v/hich are thereby outlined in green 

 against the dominant browTi of the surrounding soil. In the Dela- 

 ware colony the underlying soil is white sand rendered mediacid by 

 admixture of humus and covered by a thick carpet of upland peat 

 made up of Kahnia leaves and pine needles; and the plant grows in 

 a single compact mat, some 20 feet in diameter, being apparently 

 prevented by climatic conditions or by some parasite from spread- 

 ing into similar soil surrounding the area. 



Gaylussacia dumosa (Andrews) T. & G. 



Habitat. — Wet sphagnum peat. 



This species has been observed in but two regions, the New Jersey 

 Pine-barrens and the Coastal Plain swamps east of Washington, 

 D. C. The dominant soil reaction in both places is mediacid. 



Gaylussacia frondosa (L.) T. & G. 



Habitat. — Wet sphagnum peat, moist and dry upland peat. 

 Acidity. — 



10 3 1 



The optimum soil reaction of this species is mediacid. The low- 

 est acidity tabulated was observed in dry woods south of the New 

 Jersey Pine-barrens. 



Gaylussacia baccata (Wang.) Koch. 



Habitat. — Dry and moist upland peat and occasionally wet sphag- 

 num peat. 



^^Science, 50: 30-34, 1919. 



