32 HAY AND FODDER. 



Four species have been experimented with and found 

 to be harmful. One of these, Equisetum hyemale L., the 

 Scouring-rush or Winter Horsetail, can be dis- 



tin S uished f rom . the other three bv the fact that 

 it has an evergreen stem. This is usually un- 



branched and of considerable size, sometimes half an 

 inch or more in diameter and several feet high. The other 

 three species are all much branched. One, Equisetum 

 sylraticum L., is found almost exclusively in or at the 

 border of rather shady woods. It is a slender form with 

 characteristically leaning stem and gracefully drooping 

 whorls of branches. Another, Equisetum palustre L., is 

 practically confined to open wet places. It has rather 

 stout 4 to 7-angled, hollow branches. The above species 

 cause less trouble in this country than the fourth, which 

 is known as the Field Horsetail, Equisetum arvense, be- 

 cause of its usual habitat. This form, as stated above, 

 has separate fruiting stems which come up early in the 

 spring and bear the spore cones at their tips. Later the 

 green branched form appeai-s, no fruiting cones being 

 ever found on it. It is widely distributed and more abun- 

 dant than any of the other forms. It can be distinguished 

 from Equisetum palustre by its solid 3 to 4-angled 

 branches and by the larger cavity of its stem, this being 

 one-half to two-thirds of the diameter in Equisetum 

 t*e and about one-sixth in Equisetum palustre. From 

 Equine turn sylvaticum it is ordinarily distinguishable by 

 its much less abundant and less conspicuous secondary 

 branching. Great numbers of secondary branches do oc- 

 cur, however, on the Field Horsetail when its main stem 

 has been eaten or broken off. Then the whole aspect of 

 the plant is changed, and it assumes a low bushy form 

 that is even more distinct from the slender, graceful 

 woodland species. 



