154 FERNS IN THEIR HOMES AND OURS. 



In Chapter II. it was noted that the, Ophioglos- 

 sacecz had been found so to differ from the true 

 ferns, that they were now placed apart from these, 

 and considered only as fern allies. Of these 

 forms, O. vulgatum can seldom be kept under 

 cultivation longer than two years. Of the South- 

 ern Ophioglossums little or nothing can be said. 

 Botrychium Virginianum is by far the most grace- 

 ful of all, and the most easily cultivated. The 

 fronds of this perfect themselves in June, while 

 the various forms of B. ternatum do not appear at 

 all till August. The Botrychiums require a deep, 

 firm soil, and do not bear disturbance very well. 

 They usually grow in damp places ; but varieties 

 of B. ternatum and some of the smaller species 

 are frequently found on high pasture-land. Little 

 can be said of the minor forms ; but probably they 

 cannot be cultivated with much success. 



Among the Rhizocarps, Marsilea quadrifolia is 

 frequent in cultivation near Boston. It is a pretty 

 little plant, growing in rather shallow water. The 

 leaves, which resemble those of an Oxalis, float 

 upon the surface, while the large spore-cases are 

 borne along the creeping stems at the bottom. 

 The plant spreads so rapidly, that, in ponds where 

 it has been growing but a few years, it has every 

 appearance of being indigenous. The habitat 

 given for it in this country is Bantam Lake, Litch- 

 field, Conn. ; but the characteristics of its growth 



