266 



BOTANY 



here, Ophioglossaceae, Marattiaceae, and Isoetacese, are not closely 

 related among themselves, and the affinity of the latter with any of 

 the Ferns may be questioned. 



Order I. Ophioglossaceae 



The Ophioglossacese differ much from the typical Ferns, both in the gameto- 

 phyte and sporophyte. They constitute a small order, comprising the two 

 widespread genera, Ophioglossum and Botrychium, and the monotypic Hel- 

 mintliostachys of the East Indies. 



FIG. 230. Botrychium Virginianum. A, B, antheridia (X600). C, archegonium 



(X300). 



Gametophyte. The gametophyte is best known in Botrychium Virginianum. 

 It is a subterranean, tuberous body, quite destitute of chlorophyll, and always 

 showing a ventral mass of tissue which contains an endophytic Fungus, closely 

 resembling the "mycorhiza" associated with the roots of many saprophytic 

 Seed-plants. The presence of this Fungus is doubtless associated with the 

 saprophytic nature of the gametophyte. 



The sexual organs are borne upon the upper surface of the gametophyte. The 

 antheridia appear first and occupy a median ridge, upon whose flanks are later 

 developed the archegonia. 



