84 



VASCULAR CRYPTOGAMS 



there are species with barren and fertile leaves, differing from one 

 another in habit and in degree of segmentation ; in other heterophyllous 



-"^^ \:^v "^^^^ 



Fig, 58.— Sori of Polypodiacea: (variously magnified), a, b, Adianttini ; c, Lindsaya ; d, e, Blccknum; 

 /,g, Cystp/>t€ris : h. i^ Davallia ; k, i, CJieilanthes ; m^Ji, Pteris ; o,p,]l'ood'wa>-dia. ; q^Scolopen.' 

 driu}>i ; r, s, Aspleiiimn; t, AsJ-idiufu ; n,z', Jl'oodsia ; zv, Gymno^} ajiijiic i .x, j, PolyPodiuin. 

 (After Luerssen.) 



ferns (species of Polypodium) both forms of leaf are fertile. A fe\v of 

 the Polypodie^e are arborescent ' Dicksonia L'Herit.). 



