EQIHSETUM. SPOROPHORE. 213 



leaf-sheath, and are then seen to be continuous to the 

 apices of the teeth : between the ridges are depressed 

 channels. 



4. The Lateral branches are always inserted at 

 the nodes, and at the base of the leaf-sheaths; note 

 that they are arranged in whorls, and appear to burst 

 through and rupture the leaf-sheath near to its point 

 of insertion on the axis, and at points alternating with 

 the projecting ridges, i.e., at the channels. 



5. The Roots (to be clearly distinguished from the 

 underground root-stock, which shows an alternation of 

 nodes and internodes as above described), are thin and 

 fibrous, and branch monopodially : they are inserted 

 with a whorled arrangement at the nodes, immediately 

 below the point of insertion of the lateral buds. The 

 underground stems and the roots are covered externally 

 by numerous fine root-hairs of a brown colour. 



6. Note that at many of the nodes the lateral branches, 

 or the roots, or both may be partially suppressed, their 

 development being arrested at an early stage : also 

 that frequently the basal internode of lateral shoots 

 attached to the nodes of the root-stock may be much 

 distended, while its apical bud is arrested : in some 

 cases more than one internode may take part in this 

 development, the result being a moniliform structure : 

 the Tubers thus formed are reservoirs of reserve 

 material, and being easily separated from the parent 

 plant, they serve to propagate the plant by a purely 

 vegetative process. Any node separated from the 

 parent plant may also serve the same purpose under 

 favourable circumstances. 



7. Observe particularly that the teeth of each leaf- 



