96 



MARATTIACEAE 



[CH. 



Fig- 389. A small plant of Danaca alata ( 



stipules. (After Campbell, see Text.) 



and this is probably a priiTiitive condition. Some species oi Danaca have also 

 an erect radial shoot {D. siniplicifolia and 

 elliptica): others show at first an erect posi- 

 tion and radial construction, but this passes 

 over in the adult to an oblique position 

 with a distichous arrangement of the leaves 

 {D. alata, Fig. 389). Protomarattia and 

 Christensenia are, however, strongly dorsi- 

 ventral, with their leaves borne obliquely 

 alternate on the upper surface (Fig. 390). 

 The natural interpretation of these facts is 

 that in the last-named Ferns the primitive 

 radial and erect type has been relinquished 

 in favour of the creeping habit, which goes 

 along with a smaller bulk and greater elongation of the stem. In this they 

 resemble Helminthostachys among the Ophioglossaceae. 



The leaves are very diverse in outline, though conforming to a common 

 type. The leaf-base in all of them bears stipular enlargements laterally. 



Fig. 390. Diagrammatic representation 

 of the end of a rhizome of Christensenia. 

 7(7. = wings of the stipule; (W«.= trans- 

 verse commissure; jr,x = points at which 

 arrested apices may be found. (After 

 Gwynne-Vaughan.) 



