82 



fifty species of alg^e. These last named collecting grounds 

 offer an opportunity to study, from fresh specimens, classes 

 of plants froQi which the inland botanist is almost wholly 

 debarred. 



. The land plants of the county belong decidedly to the 

 northern flora although not so arctic in their character as 

 the lichens and algae. There is an almost total absence 

 of many species common from Cape Cod southward and 

 often found just south of Boston. In contrast to this 

 the Magnolia glauca is still quite abundant at Glou- 

 cester, but not found again north of New Jersey. At 

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

 dosa, and there also is found Potentilla tridentata, f\imiliar 

 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), Qnereus 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 my rtilloides, is occasionally 

 met wdth. 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 



