CHAPTER V. 



OPHIOGLOSSUM, Linnmus. 



(Oph-i-og-los'-sum.) 



Adders-tongue Ferns. 



HESE Ferns, with Botrychium and Helmintkostachys, represent 

 the whole of the sub-order Ophioglossacece, in which the plants 

 are distinguished by their deeply two-valved capsules opening 

 down the side nearly to the base, and being without a ring. 

 The name is derived from ophios, a serpent, and glossa, a 

 tongue ; in allusion to the arrangement of the fructification (which is composed 

 of stalkless capsules arranged in two rows so as to form a narrow, close 

 spike). Ophioglossum forms in Hooker and Baker's " Synopsis Filicum " 

 Genus 73. Though it comprises but a comparatively small number of species, 

 it is, botanically, divided into four sub-genera, as follow : 



Cheieoglossa (Cheir-og-los'-sa), Presl. In this sub-genus the fertile 

 spikes are numerous, and arise from the base of the barren segment. 



Euophioglossum (Eu-oph-i-og-los'-sum), Linnaeus. The plants belonging 

 to this sub -genus are furnished with single fertile spikes, arising from the base 

 of the barren segment. 



Ophioderma (Oph-i-od-er'-ma), Endlicher. The fertile spikes, which are 

 usually single, arise, in this sub-genus, from the centre of the barren segment. 



Rhizoglossum (Rhi-zog-lds'-sum), Presl. In this sub-genus the fertile 

 and barren fronds are distinct. 



The genus is represented in England only by the common Adder's-tongue, 

 0. vulgatum. 



