558 THE FERN FAMILY. 



( Fronds tufted, of 2 sorts, the central ones erect, fruiting, the outer ones barron, 



f>4 usually shorter, with broader lobes 6 



( Fruiting and barren fronds similar or nearly so 8 



( Fronds (stiff) simply pinnate, with entire lobes, the fruiting linear, the barren 



6< lanceolate 11. BLKCHNUM. 



( Fronds (delicate) much divided, with small, obovate or oblong, toothed lobes 7 

 / Sori forming a line close to the margin of the frond ... 6. ALLOSORUS. 

 X Sori oblong, scattered on the surface of the frond ... 6. GRAMMITIS. 

 Fructification concealed by, or intermixed with, chaffy scales or hairs . . 9 

 Fructification in lines along the margin of the fronds, the iudusium a membrane 



attached to the margin 10 



Fructification in circular, oblong, or linear sori, on the under surface, without 



chaffy scales 11 



Fronds deeply pinnatifld, with entire segments. Sori linear, concealed by the 



scales 10. CETERACH. 



Fronds twice pinnate, with small segments. Sori circular, with chaffy hairs 



intermixed 15. WOODSIA. 



Tall, erect, stiff fern, ternately divided, with pinnate branches and sessile 



lobes 12. PTERIS. 



Delicate fern, not a foot high, much divided, with broad, wedge-shaped lobes on 



capillary stalks 13. ADIANTUM. 



Sori oblong or linear, covered (when young) with a membrane attached along the 



side 12 



Sori circular, either without any indusium, or covered (when young) with a 



membrane attached by the centre or by a lateral point 13 



( Frond entire. Indusium opening in a slit along the centre 9. SCOLOPENDRIUM. 

 12 1 Frond pinnate or much divided. Indusium opening along the inner side. 

 ( 8. ASPLENIUM. 



{Fronds simply pinnate, with entire or toothed segments or pinnas . . .14 

 Fronds pinnate, with pinnatifid primary divisions or pinnas, or twice or thrice 

 pinnate* 15 



/'Segments narrow lanceolate, rather thick, attached to the stalk by a broad 

 I base, and confluent. Sori golden yellow, without any indusium. 



4 (1). POLYPODIUM vulgare. 



14 Segments distinct or stalked, ovate-falcate, prickly-toothed, with a prominent 

 angle or lobe at the base on the inner side. Sori with a small circular indu- 

 sium 7 (1). ASPIDIUM Lonchitis. 



Segments small, obovate. Indusium attached laterally . 8. ASPLENIUM. 



iving " 



10 



1ft 



Lower pair of pinnas much larger than the others, giving the frond a broadly 



triangular or rhomboidal form 16 



Lowest pair, or several lower pairs of pinnas, decreasing in size or not larger than 



the rest. Frond ovate or lanceolate in outline 17 



Fronds oncejpinnate, with pinnatifid segments 4 (2). POLYPODIUM Phegopteris. 

 16 < Fronds twice pinnate, the pinnas mostly opposite 4 (4). POLYPODIUM Dryopteris. 

 Fronds twice pinnate, the pinnas mostly alternate . . .14. CYSTOPTERIS. 

 Fronds delicate, seldom a foot high, without any brown scarious scales (or very 

 few at the base of the stalk), twice pinnate, with stalked pinnas . . 18 

 Fronds stiff, 1 to 3 feet high or more (except in Polypodium Phegopteris). The 

 stalk more or less shaggy below the leafy part, with brown scarious scales 



(except in Aspidium Thelypteris) 19 



Segments with fine pointed teeth 8. ASPLENIUM. 



Segments oblong or lanceolate, nearly sessile, with obtuse teeth or lobes. 



14. CYSTOPTERIS. 

 Segments small, obovate, stalked, with obtuse teeth. Delicate annual. 



6. GRAMMITIS. 

 pinnate, the pinnas deeply pinnatifid, the lobes entire or obtuse, and 



19-J slightly toothed . . ... .20 



( Fronds twice pinnate, the segments sharply toothed or pinnatifld . . .24 

 f Pinnas (all but the lowest pair) attached to the stalk by their broad base. 

 2<H 4 (2X POLYPODIUM Phegopteris. 



( Pinnas attached by their midrib only 21 



., / Lobes of the pinnas entire. Sori near their margins 22 



" \ Lobes of the pinna slightly toothed. Sori near their base or centre . . 23 



* In all twice or thrice pinnate leaves or fronds the primary divisions on each 

 4de of the main stalk are called pinnat, the ultimate division* retaining the name 



