12 



Cape Ann is the southern limit of the little Sagina no- 

 dosa, and there also is found Potentilla tridentata, familiar 

 at the Isle of Shoals and on Mt. "Washington. Essex 

 County seems also to be the southern limit, for this 

 region, of Pinus resinosa (Red Pine), Abies nigra (Black 

 Spruce), Vaccinium Vitis-Idsea, Viola rotundifolia, etc., 

 as it is the northern limit of Cupressus thyoides (White 

 Cedar), Quereus prinoides (Chinquapin Oak), Polygonum 

 Caryi, Draba Caroliniana, Lygodium palmatum (Climbing 

 Fern), and others. At Boxford is what has proved thus 

 far to be the only New England station for Salix Candida, 

 and another bog willow, Salix mjrrtilloides, is occasionally 

 met with. At Andover a locality for Calamagrostis Pick- 

 eringii was discovered in the summer of 1879 ; this species 

 has only been known before at the White Mountains. 

 Among the sedges and grasses, plants too frequently neg- 

 lected will be found, many not heretofore supposed to grow 

 in the county, and a careful comparison of this list with 

 our botanies will show that the range of many species has 

 been extended. Although much careful work has been 

 done there yet remains much to be accomplished ; for, be- 

 sides the few species that may be added to the list of 

 flowering plants, there are many species of lichens and 

 mosses not thus far collected, and the fungi and fresh- 

 water algse are purposely omitted altogether. The phan- 

 erogams and vascular cryptogams are quite fully studied, 

 and to the Characese and marine algse but comparatively 

 few additions may be expected. 



The early settlement of the county renders this a par- 

 ticularly favorable region for the observation of introduced 

 plants. From the earliest settlement to the present time, 

 foreign species have continued to arrive, many of which, 

 like the early colonists, came with the evident intention 

 of remaining ; for, as the genista, barberry, white-weed 



