ooi INTRODUCTION TO CRYPTOGAMIC BOTANY. 



634. Marsilea has very much the habit of Pilularia, but 

 the leaf-stalks bear several cuneiform lobes, which make low 

 starved specimens where the lobes are reduced to three, and 

 the water has dried up in which they first took their growth, 

 look very like some procumbent Leguminad, especially as 

 the hard receptacles, to the outward eye, resemble seedpods. 

 These receptacles are evidently modifications of the leaves, 

 but are more complicated than those of Pilularia. The 

 bivalved receptacle at length bursts, and a long mucilaginous 

 cord protrudes, attached to the receptacle, where its lobes 

 diverge from the peduncle. This bears on either side obovate 

 receptacles of the second order, which in an earlier state of 

 growth were connected with the veins of the primary recep- 

 tacle. Each partial receptacle is ovate, and, as in Pilularia, 

 bears a sort of placenta, which is beset on one side with spo- 

 rangia (Fig. 121, 122), on the other with antheridia. The 

 sporangia, as before, contain only a single spore, which consists 

 of a nucleus and cellular integument. The germination closely 



rig. 121. Fig. 122. 



Part of the mucilaginous cord of Sporangium of the same, 



Marsilea pubescens, with a recepta- magnified. 



cle of the second order, containing 

 antheridia and sporangia. From 

 the Flora of Algiers. 



resembles that of Pilularia. In both the stem contains a circle 

 of cavities formed by dissepiments, radiating from a central 

 mass of cellular and vascular tissue, with unreliable spiral 

 threads. MarsiUm are aquatic plants, but are not always 

 submerged. Marsilea quadrifolia is very widely diffused 

 both in tropical and temperate, but not in cold, countries. The 



