428 



Fr. J. Mathiesen. 



cellular spaces; the cells of the cortex show radial divisions 

 by thin walls of secondary formation. The endodermis is 

 exactly as in the root. The pericycle is 4 — 7 layered, its 

 cells, like those of the cortex, have somewhat thickened 

 walls. The wood-cylinder is continuous, without parenchyma- 

 rays, but is often somewhat excentrically developed, so that 

 the wood on that side of the shoots which is turned down- 



Fig. 23. Pedicularis lapponica. 



A, Portion of transverse section of runner. B, Portion of transverse 



section of flower-bearing stem. (Greenland.) (About ^"/i.) 



wards, is thinner than on the upturned side. As shown in 

 Fig. 23, Л, annual rings can be formed in the runners. The 

 two annual rings are separated by thin-walled parenchyma, 

 mixed with small vessels, and the vessels are much larger 

 in the second than in the first annual ring. Some stereom 

 (wood-fibres) is seen, especially in the inner annual ring. 



(2) The Flower-bearing stem. (Fig. 23, i?) differs from 

 the runners in that the cells of its cortex and of its only 

 1 — 2 layered pericycle, are much thinner-walled than in the 

 runners, moreover, by the Casparian spots in the endodermis 

 being much fainter, by the narrower vessels of the xylem- 



