IX] 



EQUISETUM. 



247 



two sets of buds, which may develope into ascending aerial 

 shoots or descending roots. At each node is a leaf-sheath more 

 or less deeply divided along the upper margin into teeth 

 represeating the tips of coherent leaves (fig. 52, A). 



In some species one or more internodes of underground 

 branches become considerabl}^ swollen and assume the form of 

 ovate or elliptical starch-storing tubers, which are capable of 

 giving rise to new plants by vegetative reproduction. Tubers, 

 either singly or in chains, occur in E. arvense Linn., E. silvaticum 

 Linn., E. maximum Lam., among British species. 



Fig. 53. Ehizome (R) of Equisetum imlustre L. with a thin shoot giving off 

 roots and tuberous branches from a node [after Duval-Jouve (64)]. 



In the example shown in fig. 53 {Equisetum palustre L.*) 

 the stout rhizome R gives off from its node, marked by a small 

 and irregular leaf-sheath, two thin roots and a single shoot. 

 The latter has a leaf-sheath at its base, and from the second 

 node, with a larger leaf-sheath, there have been developed 

 branches with tuberous internodes; the constrictions between 



» Duval-Jouve (64) PI. i. fig. 6. 



