150 THE SELAGINELLA RUPESTRIS GROUP. 



that name, but it was earlier given the name of 



nella strut hioloides and this is one of the names by which 



it is likely often to be called in future. 



The Prickly Mountain Moss. 



If the fern allies were placed in genera founded upon 

 external appearances alone, that plant which the British 

 call the prickly mountain moss (Selaginella spinosci] 

 would be found among the lycopodiums. It has a 

 very decided resemblance to the marsh club-moss and is 

 about the same size, but the fact that the fertile spikes 

 bear both microsporangia and megasporangia for ever 

 separates it from the true club-mosses. 



Like the bog club-moss, and unlike most of the 

 selaginellas, there is a marked difference between the 

 fertile and sterile stems. The latter are close to 

 the ground, very slender and threadlike, with occasional 

 short branches half an inch or more long. The entire 

 sterile portion seldom reaches a length of more than 

 four inches and bears roots only near the base. The 

 leaves are loosely spreading and arranged on all sides of 

 the stem. They are broadly lanceolate, acute, and the 

 margins are beset with scattered teeth too stout to be 



o 



called cilia. 



The fertile spikes grow from near the base of the main 

 sterile stems and reach a height of three inches or more. 

 They are quite erect and resemble the fruiting-stems of 

 a Lycopodimn since they consist of a leafy stalk sur- 

 mounted by a loose cone of sporophylls. The leaves on 

 the stalk are similar to those on the sterile stem, though 

 slightly larger and more closely appressed. As they 

 merge into the- sporophylls they become larger and 



