394 Fr. J. Mathiesen. 



Siberia, and Arctic Russia. This author records it also from 

 Greenland, but as it has not been found since, it ought to be 

 omitted from the flora of Greenland (Rosenvinge, M. Por- 

 sild). According to Simmons the following localities from 

 the Arctic North American archipelago can be added: Banks 

 Land, Baring Land, Victoria Land. 



Anatomy. The Root: The epidermis dies away quick- 

 ly. The primary cortex follows for a long time the growth 

 in thickness of the stele by tangential elongation of the cells, 

 accompanied by divisions in these by radial walls. During 

 the secondary growth the cambium forms oiitwards a large 

 amoimt of parenchyma, arranged in very regularly radiating 

 rows, while the formation of sieve-tissue is extremely spar- 

 ing. The cells of the parenchyma are entirely filled with 

 starch. In the woody parts the single growth-zones are easy 

 to distinguish, in an inner narrow portion of the anniial ring 

 the Vessels being surrounded by thin-walled cells, while in 

 the oiiter larger part the vessels are accompanied by wood- 

 fibres. Also in the thin-walled cells in question starch occurs. 

 Parenchyma-rays are absent. 



The Stem: As shown in Fig. 12, A and B the ring of 

 wood in the lower, persistent part of the year's shoots is 

 considerably thicker than in the iipper, perishable part. In 

 that part of the stem, from which the section shown in 

 Fig. 12 tI is taken, the epidermis, together with the outer- 

 most thick-walled cortical layer connected with it withoiit 

 intercelliilar spaces, has partly separated from the rest of 

 the cortex; this happens especially at the nodes, thus a leaf 

 occurred on the axis just above the plane of the section on 

 the side turned upwards in the figure. At the base of the 

 shoots slits are formed at some depth in the cortex (Fig. 12, 

 B and C); this explains the faet that the cortex can so easily 

 be rubbed oiT in flakes. The persistent basal portions of the 



