XIV 



L YCOPODINE.E 



499 



form elements, as in Lycopodiiini. The sieve-tubes have delicate 

 walls and numerous, but poorly developed, sieve- plates upon 

 their lateral walls. 



While in the main the anatomical characters are essentially 

 the same in all species examined, there arc a number of 

 differences to be noted/ Thus the stem may be monostelic 

 (5. Martensii), bistelic (5. Kraussiana), polystelic (5. Icevi- 

 ata). In the former species the presence of silica in the 

 inner cortex has been demonstrated bv Strasburt/cr, and 

 Gibson - has shown the same thing in other species. In this 

 species, too, besides the simple trabeculse found in S. Kraussiana, 



£'• 



^ C 



Fig. 263. — A, Rhizophore, with roots of ^'. Kraicssiana, X i j ; B, cross-seclion of the vascular 

 bundle of a root, X430 ; C, median longitudinal section of the leaf, X215. 



others occur in which the outer cells undergo divisions in more 

 than one plane, and form a group of cells with which the 

 endodermal cell is articulated. In all species examined these 

 cells show more or less marked cutinisation. The number of 

 protoxylems in most species is two, but there may be accessory 

 ones. 



The cortex is composed in most species of delicate paren- 

 chyma, with few or no intercellular spaces, and most of the 

 cells contain chlorophyll. In species like 5. leptdophylla, which 

 grow in dry localities, the cortical cells are sclerenchymatous, 



1 Gibson (2), p. 176. 



2 Gibson ( i ) 



