115 



rounded cells without intercellular spaces. In the innermost 

 layer isolated bast-cells occur. The secondary cortex, which 

 according to Segerstedt is produced on branches 3—5 years of 

 age, does not renew the epidermis as is the case in Arct. 

 alpina. There are typical annual rings, and the spring and 

 summer wood are distinctly differentiated. Now and then a 

 tendency may be traced towards the formation of irregular, ill- 

 defined annual rings, a fact which is often met with in the 

 other Ericaceœ, Rhodoraceœ and Vaccinaceœ treated in the 

 present paper. 



In the root I have not observed endotrophic hyphae (cf. 

 Hesselman). 



Except the difference in regard to the palisade-cells I am 

 not aware of having observed any other points in which the 

 specimens from other countries differed from the Danish in- 

 dividuals. 



Arctostaphylos alpina (L.) Spreng. (Fig. 28.) 



BöRGESEN, 1895, pp. 236 — 237. 0. G. Petersen, 1901, p. 75. 

 Ambronx, 1890, p. 70. 



I have had specimens for investigation from the following 

 localities : — East Greenland : Hekla Havn (N. Hartz) ; Danmarks Ö 

 (April 10, 1892, N. Hartz). Norway: (Finmark) Tromsö at Flöj- 

 fjæld'(July 24 and 27, 1885, E. W.). Sweden: Jämtland (July, 

 E. W.). Denmark : diff. localities. 



The leaf being deciduous, it naturally differs somewhat 

 in structure from that of the previous plant. Structures which 

 tend to check excessive transpiration and which are especi- 

 ally necessary to protect plants against the dryness of the 

 winter's cold, do not occur. The present species differs from 

 the above in regard to the assimilatory tissue also , which 

 is in itself peculiar as evergreen leaves do not assimilate very 

 much during winter; in short we are here dealing with quite 



a different type. 



8* 



