Horsetails 

 CHAPTER VIII 



HORSETAILS 



LIKE clubmosses, horsetails show no apparent outward 

 resemblance to ferns, to which they are related. They 

 consist of upright stems in the form of hollow cylin- 

 drical tubes solid at the nodes. These stems are leaf- 

 less, unless the toothed sheaths which spring from the 

 nodes be regarded as modified leaves. In most cases 

 the stems are branched, the branches, which are solid 

 throughout, being given off in whorls from the base of 

 the sheaths. Two of our native horsetails have barren 

 and fertile stems quite distinct in appearance. The 

 remaining six British species have both barren and 

 fertile stems nearly alike and only to be distinguished 

 by the latter bearing cones. In all the species, the cone 

 consists of a series of whorls of stalked scales, to each of 

 which are attached five or six little capsules filled with 

 spores. The stalks of the scales stand at right angles 

 to the axis of the cone, the axis being simply an elonga- 

 tion of the original stem. The scales are of an 

 irregular hexagonal form, and in the young state are so 

 close together that the interior of the cone is perfectly 

 protected from the effects of the weather. As the 

 spores mature, the axis lengthens and the scales 

 separate from each other. Then the spore capsules, 

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