THE HOMOSPOROUS LEPTOSPORANGIAT& 



379 



of phloem, separated from the endodermis by a broad pericycle. 

 In other species of Hymenophyllum, Boodle ( i ) found a dif- 

 ferent arrangement of the xylem and phloem. In some cases, 

 e g., H. scabrum, there are two xylem plates, with the proto- 

 xylem elements in the conjunctive tissues between them. 



In Trichomanes there is also a good deal of variation. Fig. 

 220, B, shows the structure in T. venosuni, a small species from 



FIG. 220. A, Section of the rhizome of Hymenophyllum recurvum, X about 40; B, 

 rhizome of Trichomanes venosum, X about 75; C, stele of B, more highly mag- 

 nified; D, root of Hymenophyllum recurvum, X about 75; E, stele of the root 

 more highly magnified. 



Australia and New Zealand. The structure of the stem dif- 

 fers from that of Hymenophyllum recurvum, mainly in its 

 greater delicacy. The sclerenchyma of the cortical region is 

 less developed, and the concentric axial cylinder corresponding 

 to its much smaller size has both the xylem and phloem reduced 

 in amount. 



In the stouter species, like T. radicans, the amount of wood 



