14 Stopes, a Nexv Fern from the Coal Measures. 



6. The Roots. 



The many adventitious roots in the specimen originate 

 from both the main axis and the petiole bases, in particular 

 there is one or more [Fig. 4, il) coming off with each 

 petiole stele as it leaves the main axis. Large numbers 

 of the roots cut in several directions are present in each 

 transverse section. They surround the axis and petioles, 

 but each one is entirely free ; there is no inclusion of the 

 roots in the stem cortex, as is so common in tree ferns 

 and the Psaroneae. They are of varying size, the larger 

 ones being about 2 to r5 mm. in total diameter. 



In some cases it is possible to see the dichotomous 

 branching in transverse section, when the stele has equally 

 divided and the cortex not yet completely separated. 



The Stele of an undividing root is of the simple diarch 

 type so characteristic of ferns, and is composed of about 

 10 metaxylem tracheides, with a group of very small 

 protoxylem elements at either end (see Fig. 6). These 

 protoxylem groups are well marked in transverse section, 

 but true spiral or annular elements have not been seen in 

 longitudinal view. The larger tracheides are clearly pitted 

 with multiseriate pits (see Fig. 7). As a rule there is no 

 trace of the soft stelar elements, a space between the stele 

 and cortex indicating their position. 



The cortex is apparently uniform, composed of 

 closely packed, rather thick-walled cells, which leave no 

 air spaces. The outer layer does not seem to differ from 

 the others, and neither root-hairs, nor exodermis has been 

 found in any of the sections examined. 



The roots as a whole shew no indications of having 

 been specialised as air or water roots, and seem to be 

 identical with the ordinary earth root of the modern fern 

 rhizome. 



