401 



The fruit may be dispersed perhaps partly by the agency 

 of animals (epizoicaliy) and partly by the agency of the wind. 



I am not prepared to state anything regarding the germi- 

 nation. Hooker (1. c.) records that the species reproduces itself 

 by gemmules; my material gave no information regarding this 

 point. Vegetative propagation takes place by the separation of 

 lateral axes. 



B. lapponicus grows in marshy localities among moss 

 {Sphagnum)-^ it appears to be rather rare wherever it occurs. 



Geographical Distribution: Arctic America and La- 

 brador, West Greenland, Spitzbergen, northern Scandinavia, 

 Arctic Russia, NovaZembIa and northern Siberia (Nathorst I.e.). 



Anatomy. The roots are usually unbranched, long and 

 filiform. Their internal structure is exceedingly loose. There 

 are no differences in the roots of plants from the different lo- 

 calities. Both the epidermis and the exodermis are suberized ; 

 towards the apex of the roots the former has thin outer walls 

 which have a tendency to collapse, but towards the base the 

 outer wall is of the same thickness as the rest of the walls; 

 the latter has slightly folded radial walls. No thickened outer 

 portion of the cortex occurs ; it is often entirely broken down 

 with the exception of a few layers of the inner and the outer 

 cortex and the trabuculae whicli connect the two last and stand 

 opposite to the woody parts of the central cylinder. The endo- 

 dermis is suberized, at any rate in the upper part of the root. 

 There are three wood masses which, in the older root, meet 

 in the middle. No mycorrhiza has been found. The starch- 

 grains are compound. 



The stem consists anatomically of three parts: the inter- 

 nodes, the nodes and the tlower-stalk. The first-mentioned are 

 characterized by the vascular bundles (3 — 6) not anastomosing 

 and being almost without stereom, and by the pith and cor- 

 tical tissue being very much broken down by age, as in JR. 

 lujperboreus. The nodes are similar in structure to those of 



