CLASSIFICATION OF THE PTEEIDOPHYTES. 127 



or completely submerged, and look like grasses or rushes. 

 They vary from a few centimetres to half a metre in height. 

 The stem is very short, and the long cylindrical leaves closely 

 crowded together. The leaves which are narrow above are 

 widely expanded and overlapping at the base. The spores are 

 of two kinds, as in Selaginella, but the macrosporangia contain 

 numerous macrospores. The very large sporangia (3fj sp.) 

 are in cavities at the bases of the leaves, and above each 

 sporangium is a little pointed outgrowth (ligula), which is also 

 found in the leaves of Selaginella. 



The quill-worts are not common plants, and owing to their 

 habits of growth and resemblance to other plants, are likely 

 to be overlooked unless careful search is made. 



