426 



SYSTEMATIC BOTANY. 



EHIZOCAEPE^E. 



Diagnosis. Asexual Generation : Small herbaceous plants float- 

 ing on the water, or rooting in the mud at the margins of pools, 



Fig. 496. 



Rhizocarpese. 



Salvinia n^ians. A, section through the plant, showing the whorls of aerial leaves I; at w 

 the submerged leaves are shown bearing,/, the sporocarps, nat. size. B, longitudinal 

 section through three fertile teeth of a submerged leaf, showing at a a sporocarp with 

 macro.sporangia, and at it two sporocarps with microsporangia : magnified. 



"M.arsilea salvatrix. C, sporocarp which has burst in water and is protruding its gelatinous 

 ring (Hanstein). D, the gelatinous ring: g, ruptured and extended; sr, compartments 

 of the sporocarp ; sch, covering of the sporocarp. E, compartment from a ripe sporo- 

 carp : mi, microsporangia ; ma, macrosporangia. 



with regularly branching stems bearing two or more series of leaves 

 circinate in vernation. Stem grows by an apical cell giving off 2 

 or 3 series of segments, and the root by one giving oil 3 series. 

 The sporocarps are metamorphosed leaves containing in one or more 

 chambers the sporangia, which spring from, a central placenta, and 

 bear one or more macrospores or numerous (4x 16) microspores. 

 Sexual Generation : The macrospores produce the female prothallia, 



