HORSETAILS 193 



CHAPTER VII 



THE EVOLUTION OF THE HIGHER SPORE-PLANTS 

 THE HORSETAILS AND THE SPHENOPHYLLS 



THE Horsetails are now a very insignificant 

 family compared with the Lycopods, for they 

 number altogether only about twenty species; 

 they are, however, more familiar to the British 

 botanist, for eight species are natives of this 

 country, and some of them are exceedingly 

 common. Every one must know the Field- 

 Horsetail, so common on railway embankments 

 and in neglected fields, and the handsome Great 

 Horsetail, sometimes six feet high, which grows 

 in swampy places, and abounds on wet sea- 

 cliffs. They are mostly striking plants and some 

 almost reach the stature of trees, for a tropical 

 American species is said to grow to a height 

 of from twenty to forty feet, though sometimes 

 aided by climbing on other plants. 



All the species have a quite characteristic 

 appearance, owing to their somewhat stiff, 

 jointed stems, and sheathing leaves. Both 

 leaves and branches (where the stem does branch) 

 are in rings or whorls. In some species, as in the 

 two common British Horsetails mentioned above 

 (Equisetum arcense and E. maximum), there are 



