angia are large, fleslu', aiul borne in boat-shaped groups Csyn- 

 angia), on the under surface of the pimiulc, near the margin. 

 The sporangia, each of which arises from a number of superficial 

 cells, are incompletely separated from one another, and remain 

 together in the oblong or capsule-like synangia. The walls of the 

 sporangium are several cells in thickness. The annulus is want- 

 ing or greath' reduced; there is no indusium. The synangium 

 is adnate to the vein, or very short-stalked. Dehiscence is first 

 by the opening of the synangial valve, then slits along each 

 sporangium. 



Campbell has made detailed studies of the gametophyte. 

 The spores are very small, bilateral or tetrahedral, and yellow- 

 ish-brown. Under suitable conditions they germinate promptly. 

 Within a week they begin to show a greenish tint, due to the 

 developing chlorophyll. The mature gametophyte is large, 

 fleshy, massive, dark-green, and heart-shaped. It grows on the 

 surface of the soil and closely resembles such liverworts as Pellia. 

 It is broad heart-shaped, tapering to a narrow base. The \ery 

 old gametophytes branch dichotomously exactly as in the thal- 

 lose liverworts. "A broad midrib extends for nearly the whole 

 length of the thallus and merges gradually into the wings, which 

 are also several-layered, nearly or quite to the margin" — Camp- 

 bell. Rhizoids, — brown, unicellular, and thin-walled, — are pro- 

 duced abundantly from the cells of the lower surface. 



The gametophyte is monoecious. Antheridia appear first, 

 sometimes on the upper surface, but usually along the lower side 

 of the midrib. The archegonia are confined exclusively to the 

 lower surface of the midrib. Campbell points out that the re- 

 productive organs are very much like those of Ophioglossum, and 

 are "marked indications of the primitiv^e nature of these ancient, 

 ferns." 



The Marattia gametophyte is always infested with a specific 

 endophytic fungus. Campbell states that it is probably iden- 

 tical with or very closely related to the fungus which occurs in 

 Ophioglossum. "In the infested cells of the green gametophyte 

 the starch and chromatophores are destroyed by the action of 



1 D. H. Campbell. The Eusporangiatae, 191 1. Mosses and Ferns, 1905. 



