XX] 



EUFILICINEAE 



283 



I. Leptosporangiate Filicales. 



In these homosporous and heteiosporous plants the sporangia 

 are developed from single epidermal cells. 



(a) Eufilicineae. The sporangia bear spores of one kind 

 only ; the wall of a sporangium consists of one layer of cells. In 



Fig. 220. Young fronds of (A) Angiopteris evecta and (B) Cycas revohita. 

 (Beduced.) 



the great majority of cases the sporangia are characterised by 

 the possession of a conspicuous row of thick-walled brown 

 cells, the annulus\ which serves as a mechanism for dehiscence 

 and spore-dispersal. The fertile leaves, identical in form with 



1 For an account of the mechanism of spore-dispersal, see Goebel (05) p. 587 ; 

 Atkinson (94) ; Leolerc du Sablon (85) ; and Bower (00). 



