DENNSTAEDTIINAE 



597 



example of departure from the strict basipetal succession ; still the receptacle 

 is seen to be elongated and traversed for a considerable distance upwards 

 by a strand of tracheides. Such exceptions occur in about one in every 

 five sori cut, and are therefore not excessively rare. These irregularities 

 are of interest for comparison with those to be described for Dennstaedtia. 

 In M. platyphylla and M. strigosa the sorus was found to be basipetal, 

 the receptacle conical, and the sporangia of the same type as in the other 

 species. Thus it may be concluded for Microlepia that the sorus is typically 

 one showing basipetal succession of rather short-stalked, slightly oblique 



FIG. 332. 



A = Microlepia spelioicac, Baker. Sorus showing unequal lips of the indusium, and 

 bttipeUl succession of sporangia. X 100. B, C = Microlepia hirta, Kaulf. Similar 

 .sections to A, but showing departures from the strict basipetal succession. X zoo. 



sporangia, with reasonable regularity of orientation, inserted up.on a conical 

 receptacle, and protected by two unequal indusial flaps. But that in some 

 species occasional departures from the strictly basipetal succession occur, 

 younger sporangia being found inserted between those which are more 

 advanced. 



DENNSTAEDTIA = (Dicksonia, Patanid}. 



This genus includes numerous species of more delicate habit than 

 Dicksonia, and with creeping rhizomes, the solitary leaves are non-articulated, 

 a character in common with Microlepia, and ranked as an important one 

 by Smith. Hairs are borne, not ramenta. The habit is like Microlepia, 

 but also very like Davallia. The small sori are marginal, and Prantl had 



