146 POLAR PROBLEMS 



little can be added to this satisfactory record; but the method and 

 rate of vegetative multiplication, where, by repeated upward growth 

 and branching of a single-rooted plant, it comes to spread over a 

 very considerable area, should be investigated. When one looks at 

 such a single-plant colony, he is deceived if he is led to believe that 

 the separate, numerous stems, many of them rooted, have had a 

 distinct origin and are independent plants. If he digs down or, better, 

 if near a placer gold mine uses the powerful jet of water used in mining 

 operations and washes away the peat and soil accumulated about the 

 stems, he will discover that he is dealing with one plant which branched 

 repeatedly at different levels representing the different layers of 

 peat, developed, for example, in succession by the upward growth of 

 mosses which enveloped the basis of the plant. This should be in- 

 vestigated in detail for all of the Arctic shrubs and trees. A powerful 

 pump, with attached fire hose and nozzle and mounted on a Ford 

 chassis, would provide the apparatus for such an investigation. 



Origin of Tussock Vegetation 



A characteristic form of Arctic vegetation are the hammocks, or 

 tussocks. The writer is familiar with these forms from personal 

 observation in Alaska and Sweden on the Arctic Circle. In Alaska 

 these tussocks are locally called "niggerheads." At Kiruna, Sweden, 

 one variety of rick is formed by the growth of various plants that 

 have invaded the tall, conical ant hills until, by the time the ants 

 have finally deserted them, the hills have been completely covered. 

 In Alaska another kind of hassock (rick) is formed by the continuous 

 upgrowth of tussock sedges (probably Carex lugens Holm), with run- 

 ways of water between. Later these hassocks may be invaded by 

 lichens, mosses, and flowering plants. The origin of these tussocks 

 and the succession of plants should be investigated. 



Survival of Arctic Plants during the Ice Age 



There is another problem about which there has been considerable 

 discussion, namely, the survival of plants in the Arctic Regions during 

 the period of most extensive glaciation. It has been demonstrated 

 that there were ice-free areas and nunataks far north of the border 

 of continental glaciation, and it has been suggested by Warming^^ 

 that these areas harbored a circumpolar flora during the Glacial 

 Epoch. Elsewhere^^ the writer has emphasized the fact that on 



16 Eugenius Warming: Om Gronlands Vegetation, Meddelelser om Cr0nland, Vol. 12, 1888, Ch. 10 

 (pp. 169-217; with French resume, pp. 239-245). See also his polemic with Nathorst: Gronlands 

 Natur og Historie: Antikritiske Bemaerkninger til Prof. Nathorst, Videnskab. Meddel. fra den Natur- 

 hist. Foren., 1890, Copenhagen, 1891, pp. 265-300. 



" J. W. Harshberger: Phytogeographic Survey of North America (in series: Die Vegetation 

 der Erde, edit, by A. Engler and O. Drude), Leipzig and New York, 1911, p. 189. See also pp. 11-13 

 of work by Ostenfeld cited above in footnote 6. 



