16 



Knud Jessen. 



probably not developed (Fig. 5,A, В ,C). The foliage-leaves 

 probably remain green during winter; when they die the three 

 leaflets fall off separately, and the stalk persists (Fig. A). The 

 floral shoot is terminal and the principal bud arises in the 

 axil of the uppermost rosette-leaf; it begins with a small 

 transversly placed scale-leaf, and opens its first foliage-leaf 

 in the year in which the parent-shoot flowers. As other 

 lateral shoots may be developed in the rosette, the plant 



Fig. 5. Potentilla tridendata. 



A, Flowering rosette-shoot; г, floral axis; the principal bud II is borne in the axil of 

 the uppermost rosette-leaf, the dead leaf-stalks are seen below the fresh leaves. B, Drawn 

 from a herbarium specimen; a scale-leaf upon an older and now flowering shoot subtends 

 a new runner. C, Apex of a runner. D, Carpel ; the ovaries are hidden by long hairs. 

 A, С are from Ivigtut, 20.8.1883; В from Ivigtut, 1868: D from Præstefjæld (A, В and 

 С about natiu-al size ; D '-U). 



may form loose tufts. The floral axis bears a few foliage- 

 leaves below the often profuse inflorescence. 



Anatomy. Only older adventitious roots have been 

 investigated. The phelloid of the periderm contains, as in 

 the rhizome, scattered thick-walled wood-cells. The cells 

 of the cork-layers are rather thick-walled. The intercellular 

 spaces are fairly large. 



The young runner is protected by a strong epidermis 

 the outer and inner walls of which measured 4.4 /^ and 3.5 /^ 

 respectively. The outermost layer of the cortex is also fairly 



