SKETCH OF THE FLORA OF ALASKA. 437 



"At Onnalaslika the mosses and licliens begin to assume that prominent sta- 

 tion which they hohl in all the very cold districts." (L. c., p. 321.) 



From all the above we may safely infer that a much lower summer temperature 

 prevails at Ounalashka than on either of the opposite main lands under the same 

 parallel. The comparative height of the snow line is also another evidence of 

 the same thing. At Ounalashka it is but 3,510 feet above the sea level, while 

 exactly three degrees further north and on the Kamtschatkan side it is 5,249 

 feet above the ocean. 



For most of the general results of botanical exploration north of Norton sound 

 we are indebted to the Report on the Botany of the Herald, by Berthold See- 

 mann, and to Dr. J. D. Hooker's paper on the Distribution of Arctic Plants. As 

 will be observed, I quote freely from both these authors. 



Seeinann says of the truly Arctic region about and north of Bchring's strait : 

 " The soil is always frozen and merely thaws during the summer a few feet 

 below the surface. But tlie thawing is by no means uniform. In peat it extends 

 not deeper than two feet, while in the other formations, especially in sand or 

 gravel, the ground is free from frost to the depth of nearly a fathom, showing that 

 the sand is a better conductor of heat than peat or clay. The roots of the plants, 

 even those of shrubs and trees, do not penetrate into the frozen subsoil. On 

 reaching it they recoil as if they had touched upon a rock through which no 

 passage could be forced. It may be surprising to behold a vegetation flourish- 

 ing under such circumstances, existing, it would seem, independent of terrestrial 

 heat, but surprise is changed into amazement on visiting Kotzebue sound, where 

 on tops of icebergs herljs and shrubs are thriving with a luxuriance only equalled 

 in more favored climes. 



" On the eastern side of America no forests are found above the mouth of the 

 river Egg, about the GOth degree of north latitude. On the western side they 

 extend as far as latitude 66° 44' north, or nearly seven degrees nearer the' pole. 



" With a sun shining throughout the twenty-four hours the growth of plants 

 is rapid in the extreme. The snow has hardly disappeared before a mass of 

 herbage has sprung up, and the same spots which a few days before presented 

 nothing save a white sheet are teeming Avith an active vegetation, producing 

 leaves, flowers, and fruit >n rapid succession." 



We further learn from Dr. Seemann that even during the long Arctic day the 

 plants have their period of sleep — short, though plainly marked as in the tropics. 

 This time of rest is indicated by the same drooping of the leaves, and other 

 signs which we observe in milder climates. 



" The whole country from Norton sound to Point Barrow is one vast moor- 

 land, whose level is only interrupted by a few promontories and isolated moun- 

 tains. 



"About Norton sound groves of white spruce trees and Salix speciosa are fre- 

 quent; northward they become less abundant, till in latitude 66° 44' north, on 

 the banks of the Noatak, Pimis [Abies] alba disappears. Ahmsviridis extends 

 as far as Kotzebue sound, where, in company with SaJix vUhsa, S. EicJiardsoni 

 and S. speciosa it forms a low brushwood. With the commencement of the 

 Arctic cii-cle Ahins viridis ceases to exist; Salix speciosa^ S. EicJiardsoni, and 

 S. villosa extend theii- range further, but are only able for a short distance to 

 keep their ground; at Cape Lisburne, in latitude 68° 52' north, they are in the 

 most favorable localities never higher than two feet, while their crooked growth 

 and numerous abortive leaf-buds indicate their struggle for existence. 



" The Esquimaux eat the roots of Polygonum viripanmi and collect for winter 

 use raspberries, whortleberries, and cranberries, which are frozen so hard as to 

 require an axe to break the mass." 



A Scdix speciosa measured by the botanists of the Herald was found to be but 

 twenty feet high and five inches in diameter, yet the annual rings showed the 

 tree had reached the age of eighty years. [For the above facts in regard to the 



