276 COVILLE 



tury. Representing as they do the three floral districts of the 

 Alaska coast — the heavily forested Sitkan flora, the forestless but 

 temperate Aleutian flora, and the all but perennially frozen Arc- 

 tic flora — the collections furnish excellent material for studies 

 in geographic distribution. Even the remaining fourth floral 

 district of Alaska, that of the Yukon Valley, in the interior 

 of the Territory, is sparingly represented in the plants collected 

 at Skagway and in Cook Inlet. 



In order to give more comprehensive scope to the work as a 

 whole, it was arranged that Dr. Trelease should devote his at- 

 tention primarily to the cryptogams, except the alga;, which 

 were entrusted to Professor Saunders ; Mr. Kearney was to 

 take the flowering plants, except the trees and shrubs, which 

 were to be left to the writer ; and the other collectors were to 

 secure such material as they could, particularly in localities 

 visited by only a few members of the expedition. A full set 

 of the cryptogamic plants is to be deposited in the herbarium 

 of the Missouri Botanical Garden at St. Louis, and a full set of 

 the flowering plants in the United States National Herbarium 

 at Washington, Dr. Trelease and the writer having in charge 

 the preparation of the reports on these groups, respectively. 



Among the genera of flowering plants that have given diffi- 

 culty to students of Alaska botany, the willows probably stand 

 first. About fifteen species were collected in Alaska on the 

 Harriman Expedition. By their habit of growth these species 

 fall easily into three groups : they either grow prostrate on the 

 ground, or form upright shrubs 2 to 6 feet high, or develop into 

 small trees. The lack of knowledge of the tree willows of Alaska 

 is shown by the fact that as late as 1896, in the ninth volume of 

 Professor Sargent's ' Silva of North America,' only two species, 

 Salix sitchcnsis and Salix nuttallii^ were credited to that Terri- 

 tory, while from our present information this number must be in- 

 creased to five. The three additional species are Salix beb- 

 bi'ana, which has been discovered in the region of Cook Inlet ; 

 the old Salix speciosa of Hooker and Arnott, a willow of 

 middle and western Alaska, which clearly attains the dimen- 

 sions of a tree ; and a ifitherto undescribed species from Yakutat 

 Bay. The key here given will serve to distinguish the species. 



