152 



MANUAL OF BOTANY 



cycle and endodermis, and they are arranged in a ring round the 

 stem. In E. silvaticum the separate steles fuse together late- 

 rally, forming a gamodesmic mass. The pericycle and endoder- 

 mis are then absent from the sides of the steles, and the portions 

 remaining behind and in front of each stele fuse together, form- 



FiG. 911. 



Fig. 912 



Fig. 911. Diagram of stem in two 

 species of Equisetum. A. E. 

 Utorale. s. The separate 

 bundles or scliizosteles, each 

 with its endodermis. B. E. 

 silvaticitm. The scliizosteles, s, 

 have their endodermis fused 

 laterally. In both figures 1= 

 cortical lacunae. After Pfitzer. 



Fig. 912. Section of vascular 



bundle of Equisetum limosum. 

 en. Endodermis. pe. Pericycle. 

 .r. Xylem. ph. Phloem. I. La- 

 cuna. After Dippel. 



ing two continuous bands, one surrounding the whole collection 

 and the other forming an internal lining to it {fig. 911, b). In 

 E. palustre the inner endodermal laj^er is not well marked, 

 the cells not thickening m the same way as those of the outer. 

 This rhizome appears to be monostelic, though it is not really so. 

 The centre of the rhizome is in most cases filled with paren- 



