FILICES 



87 



sion. In Hymenophyllum (L.) and Trichomanes (Sm.) the sporanges are 

 sessile and biconvex, and are attached to the columel by one of their 

 convex faces ; the annulus, projecting in the form of a cushion, separates 

 the two convexities, and is usually oblique, dividing the circumference 

 into two unequal portions : in Loxsoma they are pear-shaped and dis- 

 tinctly stalked. Para- 

 physes occur only in a 

 few species of Hymeno- 

 phyllum. The meso- 

 phyll of the leaf consists, 

 in the two larger genera, 

 of onlv a single laver of 

 cells, and the leaves 

 have hence a filmv and 



Fig. 63. — H yincnophylhmi •, spo- 

 ranges exposed (niagnified). 



moss -like appearance ; 

 but in Loxsoma there 

 are several layers of 

 cells, and the leaf is then 

 provided with stomates. 

 The stem is generally 

 creeping and mostly 

 very slender, and is pene- 

 trated by a single axial 



Fig. 62. — Hymenophylhan tnnhridgense (natural size). 'vaSCUlar' bundle. 



]Many species of Trichomanes are rootless ; and the stem is then densely 

 clothed with root-hairs, and slender ramifications of the stem assume 

 the appearance and function of true roots. Even the ordinary branches 

 of the stem have often been long formed before their leaves emerge from 

 a rudimentary condition. In some species of Trichomanes the fructifica- 

 tion is confined to special fertile leaves. 



The Hymenophyllace^e include but three genera, of which Loxsoma 

 comprises a single species only, of creeping habit, native of New 



