382 



PROCEEDINGS OP THE ACADEMY OF 



[Aug., 



phila arenaria (A), Cakile edentula ( = C. americana) , Myrica caro- 

 linensis, and an extensive clump of Prunus maritima (P), with an 

 occasional cedar, Juniperus virginiana (JV). In places Myrica 

 carolinensis and Hudsonia tomentosa cover extensive tracts in pure 

 association, together with Lechea maritima. 



Thicket Formation (TT). — The thickets on the more elevated 

 sandy parts of this island consist of Juniperus virginiana (JV), 

 Prunus maritima (P), Myrica carolinensis, Baccharis halimifolia, 



Fig. 2. — Portion of Plum Island Salt Marsh marked I in Fig. 1. X, Spartina 

 stricta maritima; 6, Baccharis halimifolia; H , Salicornia herbacea; 8, 

 Suada linearis; V, Spartina juncea; dotted area = sand; A, Ammophila 

 arenaria; t , thicket and forest growth. 



together with the poison ivy, Rhus radicans, while the prickly pear 

 cactus, Opuntia vulgaris, is abundant in the sandy stretches between 

 the trees. 



Plum Island is characterized by a number of salt lagoons. The 

 vegetation surrounding these lagoons was studied at two places (II 



