Rosaceæ. 



13 



palisade parenchyma usually consists of two layers which may 

 be more or less strongly developed; the leaf figured has a 

 relatively compact structure. The spongy parenchyma is 

 rather loose in structure (Fig. 4, B), and a slit-like lacuna is 

 often found within the subepidermal layer. No stereom pro- 

 per is present in the leaf, only along the main bundle some 

 bast occurs. 



Fig. 4. Potentilla palustris. (From Ivigtut in South Greenland). 



A, Epidermis and the outermost layer of cortex of an adventitious root of 



the first order ; the epidermis is about 6.5 jx high. B, Section of the spongy 



parenchyma of the leaf. C, Epidermis af the upper and D of the lower 



surface of the leaf. (A, B, «»/i; C, D, *>/i). 



At the apex of the leaf-teeth there are hydathodes with 

 water-stomata on the upper side of the teeth. 



The dark brown flower is about 25 mm. in diameter 

 (Knuth); the petals are small, about three times as short 

 as the sepals. It is usually stated that the petals persist 

 while the fruits are ripening (e. g. by Irmisch, Lindman, 

 Knuth and Neuman in "Sverige's Flora"), the sepals after 

 pollination closing round the inner parts of the flower, but 



