A mix of dried specimens of several species of "Carex" (including "Carex vesicaria") have a history of being used as thermal insulation in footwear (such as "nutukas" used by Sámi people). "Sennegrass" is one of the names for such mixes. During the first human expedition to the South Pole in 1911, such a mix were used in "skaller", when camps had been set (after each stretch of travelling had been completed). Carsten Borchgrevink of the British Antarctic Expedition 1898-1900 reported “I found the Lapps method of never using socks in their Finn boots answered well. Socks are never used in Finnmarken in winter time, but ‘senne grass’ which they, of course, had a special method of arranging in the 'komager' (Finn boots) … if you get wet feet while wearing the grass in the ‘komager’ you will be warmer than ever, as the fresh grass will, by the moisture and the heat of your feet, in a way start to burn or produce its own heat by spontaneous combustion. The great thing seems to be to arrange the grass properly in the boots, and although we all tried to imitate the Finns in their skill at this work, none of us felt as warm on our feet as when they had helped us.”