387 



of which is similar to that of R. nivalis and, as in the latter, 

 the area with the water-pores occurs almost at the margin; 

 stomata are absent from the under side of the leaf-apex. 



The leaf- s talk is reniform in transverse section. There 

 are three vascular bundles; they are without stereom. The 

 cortex often has lacunae, but otherwise resembles that of the 

 stem (Fig. 32, F.]. 



R. reptans L. 



Lit. Lange, 1887. Hartz, 1894, p. 34. Norman, 1895, p. 6. 

 Rosenvinge, 111, 1896, p. 240. 



Alcohol material from Greenland (Sophiehamn, 6.8.1883; 

 Monekordhiak, 19.7.1883); Denmark (Fure Sø, 2.9.1910). 



R. reptmis from a morphological point of view, is a tran- 

 sitional form between the preceding species and the R. lappo- 

 mcw&'-type. In the flowering plant there is a short, erect 

 rhizome which bears a rosette consisting of a few, stalked, 

 linear to linear-lanceolate foliage- lea ves, the uppermost of 

 which subtends a principal bud which may develop a floral- 

 stem with elongated internodes the same year as the parent- 

 axis flowers, but which no doubt usually develops only a rosette. 

 I am not prepared to say whether the latter may remain 

 green during winter in Arctic countries; in Denmark it passes 

 the winter in a green condition. 



The more or less filiform ærial stem becomes horizontal 

 with the formation of the first elongated internode. The inter- 

 nodes are highly curved as in R. hyperboreus. The two-rowed 

 leaves are very similar in form to the rosette-leaves and, like 

 the latter, they have a large sheath ; the uppermost ones 

 are very small, the number of leaves on the straight stem 

 differs much, 1 have in arctic specimens often found 3 — 5 but 

 14 also occurs; the creeping stem may reach the length of 

 about 50 cm. When the axis flowers it becomes ascending, 

 usually just above the uppermost leaf; the peduncle however 

 often bears a bract. The uppermost leaf upon the horizontal 



