RELATIVES OF THE FERNS 55 



circles of long outgrowths which might easily 

 be taken for leaves. For the real leaves, how- 

 ever, we must search round the upper part of 

 the stem joints, where there is a collar- like 

 arrangement with a pointed edge. Actually 

 this collar represents a series of leaves joined 

 together at the base. These are not specially 

 green, and the work which the foliage of most 

 plants carries out is here performed by the stem 

 and the circles of outgrowing branches, which 

 have already been mentioned. 



As a whole, it will be noted that the stem of 

 the Horsetail is ribbed, and is very hard to the 

 touch ; this is chiefly due to the large amount 

 of silica which is present as a strengthening 

 material. The stems are hollow to a large 

 extent, save at the joints, where there is a 

 certain amount of solid matter for the strengthen- 

 ing of the plant. These green stems of the 

 Field Horsetail play no part in the reproductive 

 scheme of the plant, other than the securing 

 of food supplies for the extensive system of 

 roots which are below the level of the soil. 

 The fertile shoots are to be found quite early 

 in the season, and in a mild spell may be looked 

 for during the latter part of March. They are 



