210 



Fr. J. Mathiesen. 



of the flowers (fig. 23, A). This figure also shows that the 

 style of D. jrigidum only reaches a few mm beyond the 

 anthers. The papillae of the stigma are fairly long (fig. 23,2)). 

 Anatomy. The adventitious roots are 3 — 5 rayed, with 

 the central-cylinder surrounded by a strong endodermis (fig. 

 24,5), Some cells with thin walls occur scattered in this, 



especially opposite the 

 hadromal rays. The 

 primary cortex consists 

 of a rathe r thickwalled 

 parenchyma, of 16 — 20 

 layers. The outermost 

 layer developes into an 

 exodermis which in tan- 

 gential section (fig. 24, 

 D) shows both axially 

 extended cells and short 

 almost isodiametrical 

 cells; these latter are 

 comparatively thinwal- 

 led. The middle lamella 

 is undulated, and in 

 older roots (these alone 

 were at my disposal) 

 it is cutinised all round 

 the cells, and this was 

 also the case with the 

 middle lamella of the 

 endodermis. A trans- 

 verse section of the outer layers of the root is illustrated 

 in fig. 24, C; the fourth cell in the exodermis, from below, 

 is one of the above-mentioned short and thin-walled cells ; 

 these are frequently filled with a brown coloured substance, 

 similar to that which characterises the epidermis and the 



Fig. 24. Dodecatheon frigiduin. 



A, transverse section of a root-branch. B, the central- 

 cylinder with endodermis and a layer of the surround- 

 ing cortical parenchyma of an adventitious root; the 

 starch contents are shewn in some of the cells. C, the 

 outer layers of the adventitious root. D, a tangential 

 section of the exodermis. (4,B, С and D,ob]A, oc.4.) 

 (Herschell Island.) 



