THE HOMOSPOROUS LEPTOSPORANGIAT^ 



389 



show a certain likeness to Botrycliiuni. J he sporangia arise 

 always in acropetal order from the apex of the terminal seg- 

 ments (sorophore) of the sporophyll, and are strictly lateral in 

 origin, not originating from epidermal cells, but from marginal 

 ones. The young sporangium api)ears as a lateral outgrowth 

 of the margin, exactly like a young pinna upon the main axis, 

 and the young sorophore has the appearance of a young pinnate 

 leaf, and at this stage recalls strongly the similar one in Bo- 

 trychium. This is especially marked in Aneimia and Lygo- 



FiG. 227. — Cibotium Mcnziesii. A, Pinnule with the sori {s), X3; B, a single sorus 

 showing the two-valved indusium, X9; C, a single sporangium, X80; r, the 

 annulus; D, a paraphysis, X8o. 



dium, less so in Schiscea, where the sporangia are smaller, and 

 the mother cells project much more strongly. The early divi- 

 sions correspond closely with those of the Hymenophyllacese, 

 and as there the tapetum is massive and two-layered, and the 

 stalk of the sporangium very short. The wall Is derived in 



The divisions in the wall are too complicated to be explained without 

 numerous figures. See Prantl's figures, Plate V.-VIII. 



