1 88 



THE MARSILIACE^E. 



Marsilia. 



to any of the fern allies. The leaves of the marsilias 

 are ahvays four-parted, with slender petioles and much 

 resemble those of oxalis or four-leaved clovers. Those 

 of Pilularia are slender tapering organs, in outward ap- 

 pearance like the leafstalks of their relatives. In both 

 genera the leaves rise from a jointed branching rootstock 

 growing parallel to the earth and sending down abun- 

 dant rootlets from the joints or occa- 

 sionally from other parts of the stem. 

 The leaves are coiled in the bud, like 

 those of the ferns, and in Marsilia they 

 are veined like them. 



The sporocarps are from one to six 

 in number and are borne on short pedi- 

 eels that spring from the petiole of the 

 leaf. Usually they are so close to the 

 stem as to appear to be borne in the axils of the leaves, 

 though in one exotic species, Marsilia polycarpa, they 

 often number as many as twenty, and are strung along 

 the petiole for some distance, each on 

 a separate pedicel. In Pilularia they 

 are usually solitary. In Marsilia the 

 sporocarps are oblong, and in Pilula- 

 ria they are round. From their shape 

 and size, like peppercorns, the mem- 

 bers are sometimes called pepperworts. 

 The Pilnlaria sporocarp contains from 

 two to four chambers, each of which 

 contains a single sorus bearing megasporangia at the base 

 and microsporangia at the tip. The megasporangia each 

 contain but a single megaspore, while the microsporangia 

 contain numerous microspores. In Marsilia each half 

 of the sporocarp may be considered as a single cell, but 



Sporocarp of Marsilia, 



(Enlarged.) 



