XXIIIj 



COMPARISON 



t8q 



Fig. 469. Marsilea quadrifolia. A, section through the "raphe" of the sporocarp, showing by the 

 orientation of the meristele that the raphe marks the abaxial side. B, young leaf, showing the 

 lateral insertion of the young sporocarp. C, relations of stem (5), leaf (/.) with its median plane 

 (;«, ;«), and two sporocarps (/^, /"„). D, dorsal, V, ventral directions. (/? and C after Duncan 

 Johnson.) 



stantly an undivided leaf-trace and pinna-trace: that these pinnules are 

 folded towards the ventral side, which is directed downwards, and there fuse 

 laterally: while the space between is filled by an upgrowth of tissue forming 

 the "indusium." In support of this view a comparison with one of the simplest 

 of the Schizaeaceae, viz. 5. riipestris, may be made: its sterile leaf is flattened 

 but simple, as it is in Pilularia. The fertile leaf bears 6-10 slender, spreading, 

 serrated spikes on each side. These are shown in Fig. 470, and are recognised 



Fig. 470. Young leaves of Schizaea rupatris, showing 

 circinate vernation with the pinnae reflexed to the 

 convex (abaxial) side. ( x 6. ) 



as pinnae reflexed so that their lower surfaces, to which the originally 

 marginal sporangia are directed, face inwards. A transverse section through 

 them is shown in Fig. 471, A, and a longitudinal section in Fig. 471, B: 

 while their natural position relatively to one another is shown in Fig. 471, C. 



