392 



sliows a leaf transitional between llie two types; the niesopliyll 

 of the ii|)ppr surface is pahsade-like, and th(Me are three himdies. 

 The bundles arc witliout stereoin, hut iiave a more or less 

 distinct sheath containing clilorophyll. 



Each leaf-apex has an e pi them a which opens at the 

 margin (Fig. 35, G). The cells have highly undulating walls, 

 similar on the whole to those in /<*. nivalis. 



R. liyperl)oreus Rottb. 



Lit. Hooker, 1833. Lindman, 1887, p. 41, fig. 8 a, b, tab. I. 

 Hartz, 1894, pp. 6, 34; 1895, (II), p. 289. Norman, 1895, p. 8. Rosen- 

 viNGE, I, 1892, p. 675; III, 1896, p. 108. Krudse, 1897, p. 385. 

 Abromeit, 1899, p. 30. Andersson & Hesselman, 1900, p. 47. 

 Resvoll, 1900, fig^-., 4, 5, 13, 20, 22, 23, 25, 27, 28, 30, 33. 

 Düsen, 1901, p. 30. Porsild, 1902, pp. 170, 196, 205. Simmons, 

 1906, p. 115. 



Alcohol material from Greenland (Friedrichsthal, 29.8. 1883, 

 Jacobshavn, 25.7.1884, Sermilik, 3.7.1885, Kingigtortadlit, 

 1.7. 1887, Uperniviarsuk, 9.7. 1887, Niodluisuk-0en, 21. 8. 1888). 

 Iceland (Thingvellir, 13. 6. 1895). Lapmark (Bosekob, 3. 7. 1884). 

 Spitzbergen (Gåseoen 28.7.1882). 



R. hyperhoreus bears a great resemblance to R. lapponicus 

 but is distinguished from the latter mter alia by the form of 

 its leaf, by its more abundant branching, and by its much 

 shorter flower-stalks. The leaf is deeply tripartite, the lobes 

 are narrower than in R. lapponicus^ the middle one is entire 

 and the lateral lobes are often shallowly 2-lobed (Fig. 36). The 

 leaves are placed in two rows upon the slender stem the inter- 

 nodes of which are curved. The internodes may reach a length 

 of 10 cm. Usually every leaf subtends a lateral shoot which 

 is antidromous to the main axis. The first leaf of the shoot 

 is situated dorsally and somewhat sideways, and its internode 

 is elongated. It is no doubt usual for 3—4 generations of axes 

 to attain the flowering-stage during the same year; the first 



