430 



Fr. J. Mathiesen. 



walls; those of the epidermis of the lower surface (Fig. 24, C) 

 are more strongly undulating. The lateral walls of the epi- 

 dermal cells of both the upper and lower surface, althoiigh 

 thin, are yet very distinctly porose, those of the upper sur- 

 face, more- strongly so. Stomata occur only upon the lower 

 surface, the guard-cells are surrounded by 4 — 6 cells. In trans- 



verse section (Fig. 24, A) 1 — 2 

 layers of palisade-cells areseen; 

 the spongy parenchyma is 

 composed of highly-branched 

 cells (the small circles inside 

 the cells of the spongy paren- 

 chyma indicate the branches 

 which have been cut through 

 on preparing the section); 

 chlorophyll-grains are present 

 abundantly in the whole of 

 the mesophyll, also in the epi- 

 dermis of the lower surface; 

 the stomata occur on a level 

 with, or are raised slightly 

 ■ above, the leaf-surface. The 

 fmal branchings of the veins end in an epithema-like tissue 

 of somewhat inflated, thin-walled tracheids. 



Very characteristic of the leaves of the Pedicularis spp. 

 are the numerous glandular hairs of the type shown in 

 Fig. 24, A and C. Fig. 25 shows a portion of a leaf-section 

 seen from the lower surface,* — the glandular hairs are found 

 here only — , the veins are drawn as if visible through the 

 mesophyll, and the glandular hairs are seen to be crowded 

 under the veins, the same feature is recorded by Hovelacque 

 (1. c.) in the case of other species of Pedicularis. In Fig. 24, C 

 three glandular hairs are seen from above; the epidermal 



Fig. 25. Pedicularis lapponica. 

 A portion of a leaf-section seen 

 from the lower surface; the 

 glandular hairs are seen to be 

 crowded under the veins (about 

 'Vi). 



