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PLANT MORPHOLOGY 



Fig. 253. Female gametophyte of Marsilea quadrifolia. A, longitudinal section of 

 megaspore; B, archegonium initial cut off at apex of spore; C, young archegonium with 

 central cell surrounded by neck cells and sterile jacket; D, mature archegonium, showing 

 large egg, small ventral canal cell, and neck canal cell; E, two-celled embryo; F, embryo, 

 enclosed by cal.\ptra, showing differentiation into foot (/), root (r), leaf (I), and stem (s) ; 

 A, XlOO; B to F, X250. 



arrangement of the segments is such that the two outer segments (those 

 nearer the neck of the archegonium) give rise to the leaf and root, the two 

 inner ones to the stem and foot, the leaf and stem developing from seg- 

 ments on the same side (Fig. 253F) . With respect to the arrangement of 

 the primary organs, the embryo of the Marsileaceae is similar to that of 

 the Filicales. 



