96 



developed on the lower parts of the year's shoots, is formed 

 of cork-tissue in the customary manner (Segerstedt p. 29). 



There is no difference between the elements of the spring 

 and summer wood (O.G.Petersen, p. 78): the limits of the 

 different annual rings are sharply defined, but it is difficult to 

 decide where each annual ring begins (Fig. 16). If the thick 

 line seen in Fig. 9 indicates the completion of the annual ring 

 then the wood first formed is unusually marked and small-celled, 

 if not then it is difficult to explain the presence of this line. 



I have not examined the roots. (Hesselman, p. 27). 



boiseleuria procumbens (L.) Desv. (Figs. 13—14). 



Warming, 1885, p. 31; idem., 1887, p. 111. Borgesen, 1895, 

 pp. 236 — 237. Ambronn, 1890, p. 70. Tedin, 1892, p. 75. O.G. 

 Petersen, 1901, p. 78. 



I have had specimens for investigation from the following 

 localities: — West Greenland: Godthaab (June 28, 1884, Th. 

 Holm); loc. ign. (July 28—30, 1885); tent 17 (Aug. 30, 1886, 

 Ryder); tent 14 (July 13, 1887, Ryder); Finmark: Tromsö (June 

 28, 1885, E. W.); Bosekop (July 3, 1885, E. W.). Iceland: 

 Mossfellsheidi (June 14, 1895). Norway: Tronfiæld (F. Borgesen); 

 Storlien (F. Borgesen). 



The leaf is subericoidal. The margins of the leaves are 

 somewhat bent inwards, and as the midrib stands out conspi- 

 cuously on the lower surface a kind of furrow is formed on 

 either side of the midrib. 



The upper and lower epidermis are very much thickened by 

 the presence of a cuticle and beneath it a cuticularized layer 

 except in such places between the margin of the leaf and the 

 central ridge where protective, unicellular hairs occur. The 

 epidermis is however thicker in this plant than in Bryanthus. 

 Mucilaginous membranes are seen in the inner wall of the 

 cells of the epidermis, on their surface and sides (but not in 



