THE MARSILIACEAE. 



! N account of the way in which the 

 spores originate, the Marsiliaceae 

 and Salviniaceae are believed to be 

 closely allied. They present several 

 differences, however, quite as strik- 

 ing as their resemblances. All are 

 lovers of the water, but while the 

 species of Salviniacea^ are floating, those of the Marsili- 

 aceae are rooted in the mud in swampy places or at the 

 bottom of ponds. The species of the first are all 

 regarded as annual, while those of the latter are said to 

 be perennial. Both bear their spores in sporocarps, but 

 these are very different structures in the two families. 

 In the Salviniaceae the sporocarp represents a single 

 sorus like that of ordinary ferns; in the Marsiliaceae the 

 sporocarp is really a modified leaf and contains several 

 sori. It may be likened to the berry-like structure that 

 encloses the sori in the sensitive fern (Onoclea). Like 

 the Salviniaceae, this family also consists of two small 

 genera, Marsilia and Pilularia, both most abundant in 

 the waters of the warmer parts of the globe. 



Although more closely related to the ferns than any of 

 the other fern allies, the Marsiliaceae are far from ferns 

 in appearance. Nor do they have a greater resemblance 



