FIELD HORSETAIL. 



126 



ridges. The accompanying cuts represent half-sections 

 through the stems of the principal British species. In this 

 species there are about a dozen blunt ridges on the stem, 

 extending right to the points of the leaf-sheath. The branches 

 are four-angled, solid, and jointed and sheathed like the main 



Half-Sections through Horsetail Steins. 



1. Equisetum maximum. 4. E. sylvaticum. 



2. ,, pratense. 5. ,, limosum. 



3. ,, arvense. 6. ,, palustre. 



7. E. hyemale. 



stem. The cells of the cuticle secrete silica in such quantity 

 that the whole of the vegetable matter may be got rid of by 

 maceration, yet the form of the stem will remain in this trans- 

 parent skeleton of silica. Certain species are used for polishing 

 metal, under the name of Dutch Rushes. 



So far we have been describing what is known as the barren 



