22O 



A FREE-LIVING SPOROPHYTE 



For my own part, I am satisfied to regard them as belonging neither to 

 the category of stem nor of root, but as a result of development to meet 

 a certain need, and that the growth produced was not of either character 

 in phyletic origin. 1 



It is interesting to compare Selaginella with the allied fossils, which 

 have as their underground system the enigmatical Stigmarian development 

 (Fig. 112). These underground parts of Lepidodendron and Sigillaria 

 present morphological questions somewhat similar to those of Selaginella : 

 the main Stigmarian trunks are not roots, for their anatomical structure 



Fl(i. 112. 



Ground plan of a Tree-stump with Stigmaria-trunks. One-sixtieth the natural size. 

 (After Potonie.) 



is far removed from that of any known roots ; they are not typical rhizomes, 

 for the only appendages they are known to bear are the Stigmarian 

 rootlets, which are rightly so recognised from their anatomical features. 

 They may be best classed with the rhizophores of Selaginella, or more 

 especially with the basal knot on the hypocotyl of S. spinulosa (Fig. 113), 

 though the correspondence is far from being exact. These, the Stigmarian 

 trunks, and the curious processes in Pleuromoia (Fig. H4), 2 may all be 

 held to be outgrowths which fall into no recognised category of parts, such 

 as stem, leaf, or root ; and they all serve the same purpose, of acting as 

 a basis of attachment for the roots themselves. The existence of such 

 bodies points to the Lycopodiales as presenting characters of peculiar 



1 Cf. Goebel, Flora, 1905, p. 209. 



Solms, Bot. Zeit., 1899, p. 227. 



