FILICES. 255 



Compare with the Type : Common Polypody (Poly- 

 podium vulgare), simply pinnatifid fronds, with naked 

 sori (no indusium) : Hart's-tongue (Scolopendium vul- 

 gare\ undivided, broadly linear fronds, with diverging 

 linear sori on each side of the mid-rib : Hard Fern 

 (Blechnum Spicant), with two kinds of simply pinnate 



Fio. 198. Pinnjile of Adiantum. 



fronds ; some being barren (without any sori), the others 

 with two linear sori, one on each side the mid-rib of 

 each segment of the frond : Common Brake (Pteris 

 aquilina) with large branching fronds from a creeping 

 rhizome, and narrow sori along the margin of the 

 pinnules : Royal Fern (Osmunda vulgaris), with the 



FIG. 199. Pinnule of Polypodium. 



sporangia clustered on the upper divisions of the frond, 

 forming a panicle, the lower portion of the frond 

 being leafy and barren ; the sporanges open across the 

 top : Moonwort (Betrychiutn L^{nar^a) ) with a sporange- 



