CHAPTER XXIX. 



HORSETAILS. 



571. Among the relatives of the ferns are the 

 horsetails, so called becaiise of the supposed resem- 

 blance of the branched stems of some of the species 

 to a horse's tail, as one might infer from the ])lant ^ 

 shown in fig. 325. They do not bear the least re- 

 semblance to the ferns which we ha\'e been study- 

 ing. But then relationship in plants does not depend 

 on mere resemblance of outward form, or of the promi- 

 nent part of the |ilant. 



572. The field equisetum. Fertile shoots. — Fig. 

 321 represents the common horsetail (Erpiisetum ar- 

 vense). It grows in moist sandy or gra\"elly places, 

 and the fruiting portion of the plant (for this species 

 is dimorphic), that is the jiortion whii h bears the 

 spores, appears al)0\"e the ground earh' in the spring. 

 It is one of the first things to peep out of the recently 

 frozen ground. This fertile shoot of the plant does 

 not form its growth this early in the s]iring. Its 

 development takes place under the ground in the 

 autumn, so that with the ad\-ent of spring it pushes 

 up without delay. This shoot is from 10 to 20 

 cm high, and at ipiite regular intervals there are 

 slight enlargements, the nodes o( the stem. The 

 cylindrical ])Ortions between the nodes are the 

 internodes. If \\e exann'ne ihe region of the inler- 

 nodes <arefull\' we note that tlicre are linn mem ', 

 branous scales, more or less t riaiigular in outHiic. andj^'i 

 connected at their bases into a ling around tlic stem. f,-uiii„g spike. 



III! 



