FRUCTIFICATION IN FERNS. 13 



In § Campyloneuron the areolae, each usually bearing two 

 sori, are found between the parallel primary veins which extend 

 from the midrib to the margin. 



31. Gymnogramme — In this genus the sdri follow the 

 course of the veins, and consequently vary with the venation, 

 being simple, forked, pinnated, or anastomose with each other. 

 The sori are non-indusiate. 



32. Notholaena. — In the cloak-ferns the sori are marginal, 

 and provided with no indusia. This genus is linked very closely 

 to Gymnogramme on one hand and to some species of Chei- 

 lanthes on the other. From the latter it is separable only by the 

 absence of the marginal indusium; the two are likely to be con- 

 founded by beginners. 



33. Taenitis has simple fronds, and the fructification in a 

 continuous sub-marginal line near the apex of the frond. 



34. Vittaria. — This peculiar genus occupies a somewhat in- 

 termediate position between the indusiate and non-indusiate 

 genera, and while usually associated with the latter has consid- 

 erable claim to be ranked with the former. The fronds are nar- 

 row and grass like, bearing the sporangia in an intramarginal 

 groove, often more or less covered by the inrolled edge of the 

 frond. The venation is very obscure. 



35. Adiantum (Fig. 5). — The maidenhairs have a peculiarly 

 smooth foliage, and usually possess no 

 midvein. The veins are usually fiabellate, 

 and after forking one or more times bear 

 the sori at their extremities. The margin 

 of the frond is refiexed, thus forming an 

 indusium which bears the sporangia on its 

 under surface. i^'g. 5.— a segment of 



Adiantum^ showing the 



36. Pteris (Fig. 6). — In this genus, sori covered by indusia 

 ,.,.,,", , , , • formed by reflexions of the 



which mcludes the common brake, the marginof thefrond -From 



otherwise free veins are united by a fili- Le Maout and Decaisne. 

 form receptacle which bears the sporangia. This continuous 

 marginal line of fructification is covered by a membranous in- 

 dusium formed of the margin of the frond. 



37. Cheilanthes. — The lip-ferns found within our limits 

 are unequally divided among four sections, all agreeing in bear- 



