1902] THE ECOLOGY OF THE DELAWARE COAST 3^5 



Salsola almost invariably occur, although their accompanying 

 forms, Xanthium and Atriplex, are not so widely distributed. 

 On the dunes the character plant, Ammophila, is of northern 

 distribution, and is not found south of Chesapeake bay, but is 

 abundant on the Michigan coast. Of its associates, Euphorbia 

 polygonijolia, Leptilo?i canadense, and Cenchrtis tribuloides are widely 

 distributed, Panictint amarum is absent from the lake flora, and 

 Oenothera humifusa extends along the Atlantic coast only to 

 New Jersey. 



Back of the first line of dunes, the combination of low dunes, 

 swamps, and meadows offers a wide choice of habitat for plants, 

 and we find many plants of wide range. The dune -holder 

 Hiidsonia tomentosa is a plant of northern distribution, Maryland 

 being its southern limit, but it has a western range. Associated 

 with Hudsonia, such forms as Myrica cerifera and Baccharis 

 halmifolia are distributed along the Atlantic coast, but neither is 

 found on Lake Michigan. Many grasses, sedges, and legumes 

 are widely spread and need not be taken into consideration. 

 Strophostyles helvola^ very characteristic in Delaware, is mentioned 

 only in the reports from New Jersey and Mississippi. Spartina 

 pate?is shows a preference for salt conditions, appearing all along 

 the sea and gulf strand, but not forming a part of the lake flora. 

 Among the plants characteristic of the heath we find some 



widely distributed grasses and 



Ju?nperus 



virginiana stands out preeminently the most widely spread. 

 Qtiercus digitata and Diospyros virginiana extend from Rhode 

 Island and New York to the gulf; Rhus copallina is mentioned 

 only in the New Jersey and Virginia floras ; while the widely 

 spread Rhus radicans {R, Toxicode^idroti) was found at Rehoboth 

 in only one situation in the woods. Of the pines, Pinus Taeda^ 

 reaching (according to Britton and Brown) its northern limit in 

 Delaware, was not found, although it is reported at Cape May, 

 the peculiar conditions there obtaining accounting for its 

 presence. ^^ Pimis rigida and P. virginiana^ however, extend 

 north and south of this region. 



'3HARSHBERGER, 632. 



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