PTERIDOPHYTA. 



211 



others each leaf has at its base an intrapetiolar, cap-like sheath, 

 which protects the succeeding leaf. The leaves are of two kinds : 

 (a) foliage, which in Ophioglossum vulgatum are lanceolate and 

 entire, but in Botrychium however, are pinnate (6 in Fig. 208 

 J, J5); and (6) fertile, which are found facing the upper side of 



3. .4 Oi Jiioglossum vulgatufn, (Adder's-tongue) : B Botrycliium lunaria (Moon- 

 wort), both natural size ; r-n-oots; bs leaf-stalk ; ststem; l> foliage-leaf ; /fertile leaf. 



the foliage-leaves. These latter in Ophioglossum are undivided 

 and spike-like (Fig. 209 A), but pinnate in Botrychium (Fig. 208 B). 

 Each foliage and fertile leaf are branches from the same petiole. 

 The large sporangia are placed laterally, and open by two valves. 

 No annulus is formed (Fig. 209). Ophioglossum reproduces vege- 

 tatively by adventitious buds on the roots. 



