ALPINE AND ARCTIC PLANTS 445 



Some hardy species climb from the plains to heights of 

 5,000 feet or more, with scarcely even the usual change of 

 being depauperated, and then suddenly disappear. This is 

 very noteworthy in the case of two woodland plants, the dwarf 

 cornel or pigeon berry (Cornus Canadensis), and the twin- 

 flower (Linncea borealis). The former of these is a plant most 

 widely distributed over northern America, and probably be- 

 longs to that newer flora which overspread the continent after 

 its re-elevation. In August this plant in the woods around the 

 base of Mount Washington is loaded with its red berries. At 

 an elevation of four to five thousand feet it may be found in 

 bloom ; above this a few plants appear, destitute of flowers, 

 dwarfish in aspect, and nipped by cold, and then the species 

 disappears. No doubt the birds that feed on its little drupes 

 have carried it up the mountain, and have sown it a little 

 farther up than the limit of its probable reproductiveness. 

 The beautiful little Linnaa is a still more widely distributed 

 plant ; for it occurs on the hills of northern Europe, and is 

 found across the whole breadth of the American continent 

 from Nova Scotia to the Columbia River. It is almost beyond 

 question a member of the old Arctic flora which colonized the 

 islands of the Pleistocene sea, and has descended from them 

 on all sides as the land became elevated. This plant also 

 climbs Mount Washington to a height of 5,000 feet, and pre- 

 sents precisely the same characters on the top as at the bottom, 

 only losing a little in the length of its stem. Specimens bear- 

 ing blossoms, and quite in the same stage of growth, may be 

 collected at the same time on the highest shoulders of Mount 

 Washington, and on the flats at Gorham. The Ltnncea in this 

 is true to its designation. For, as if it belonged to it to sup- 

 port the reputation of the great systematist after whom it is 

 named, it preserves its specific characters with scarcely a tittle 

 of change throughout all its great range. One cannot see this 

 hardy little survivor of the Glacial period, so unchanging yet so 

 5. E. 32 



