220 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.! 
It is interesting to compare Se/ag?ne//a with the allied fossils, which 
have as their underground system the enigmatical Stigmarian development 
(Fig. 112). These underground parts of Lepidodendron and Sigillarta 
present morphological questions somewhat similar to those of Se/ag/nedla : 
the main Stigmarian trunks are not roots, for their anatomical structure 
Ground plan of a Tree-stump with Stigmaria-trunks. One-sixtieth the natural size. 
(After Potonié.) 
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 Se/agine//a, or more 
especially with the basal knot on the hypocotyl of .S. spizulosa (Fig. 113), 
though the correspondence is far from being exact. These, the Stigmarian 
trunks, and the curious processes in Plewromoia (Fig. r14),” 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 
"Cf. Goebel, Alora, 1905, p. 200. *Solms, Bot. Zerl., 1899, p. 227. 
