THE SELAGINELLA RUPESTRIS GROUP. 



141 



differ from the ordinaiy foliage leaves only in being 

 broader at base and having rather more numerous cilia. 

 They are arranged in four ranks, a row on each of the 

 four angles of the spike, with the bases 

 closely over-lapping. The spikes are from 

 half an inch to an inch long. After the 

 spores have fallen, the sporophylls be- 

 come reflexed, and the sporangia, split 

 nearly into halves, spread out in the axils 

 like small greenish flowers. The megas- 

 porangia are supposed always to bear 

 four megaspores, but all four do not 

 always develop. They are bright orange 

 yellow in colour and are large enough to 

 be seen with the unaided eye. They are 

 borne so plentifully by this species that 

 they are often noticeable on the ground 

 about the plants late in autumn. The 

 megaspores and microspores are said to 

 be borne in the same leaf axils. 



Until a few years ago Sclaginclla ritpcstris was consid- 

 ered to be a widespread though somewhat variable 

 species. Recently, however, it has become the fashion 

 to describe each form as a distinct species, no matter 

 what its characteristics, and about forty of these forms 

 have been so described. It can scarcely be doubted 

 that the species, as once regarded, covered too great a 

 range of forms ; but it is equally certain that many of 

 the newly described species are mere forms due to con- 

 ditions of environment. The points most relied upon 

 for separating them are the presence or absence of the 

 bristle tips of the leaves and the number of cilia on the 

 leaf margins. Only the more noteworthy forms can be 



Spike of Rock 

 Selagjnella. 

 (Enlarged.) 



