Rosaceæ. 27 



(Fig. 9, С). The outer wall of the upper epidermis in /, elatior 

 is 2.5 — 3.5^ thick; in f.humilis from Lille Snenæs it was 

 found to be about 6.5//; the inner wall is mucilaginous (Fig. 

 9, B); the radial walls are straight (Fig. 9, D)\ in the lower 

 epidermis they are wavy (Fig. 9, E). In the palisade paren- 

 chyma also a difference was found between the two forms, there 

 being 2 layers in /. elatior (Fig. 9, B), but 3 layers in /. humilis. 

 which is on the whole somewhat more xeromorphic. The 

 spongy parenchyma is rather loosely built and consists of 

 somewhat branched cells (Fig. 9, F). Bast either does not 

 occur or is slightly developed only along the strongest bundles. 

 The yellow petals are slightly longer or according to 

 Simmons usually only just as long as the sepals, and the 

 diameter of the flower is about 10 mm. (Wolf); there are 

 20 stamens with short filaments. According to the alcohol 

 material from Snenæs in Greenland the species appears to 

 be homogamous. In the young flower which was just opening 

 the anthers were found to be closed, and the short, slightly 

 lobed stigma had not as yet received pollen (Fig. 7, C). In an 

 older flower some of the stamens were bending with open 

 anthers inwards towards the pistils, and the appearance 

 of the stigmas was as shown in Fig. 7, D; they were densely 

 covered with germinating pollen. Spontaneous self-pollina- 

 tion probably occurs. Pot. piilchella flowers in July; in Spitz- 

 bergen flowering begins at the end of June and is continued 

 into September. Fruit is set regularly and abundantly {A. 

 and H.; Simmons). 



Potentilla nivea L. 



Lit. Bonnier, 1894. Hartz, 1894, p. 6 ; 1895 a, pp. 287, 

 300; b, p. 322. Norman, 1895. Kruch, 1897. Abromeit, 1899. 

 Andersson and Hesselman, 1900. Cleve, 1901. Sylvén, 1906. 

 HoLLSTEiN, 1907. Wolf, 1808. 



This species grows on rocks, and on rocky and grassy 

 flats; it avoids well-aerated moist soils (Cleve). It is circum- 



