17 
17 
1.9 
19 
23 
23 
23 
23 
27 
27 
- 3 - 
16 - Leaf blades more than one layer of cells thick* sporangia 
stalked* borne on side of the tube* annulus complete ....... Sphenomeris 
16 - Leaf blades one layer of cells thick* sporangia sessile* borne 
upon a receptacle* annulus incomplete (Hymenophyllaceae) 17 
Stipes and fronds hairy. ..............,.., ... 18 
Stipes and fronds glabrous. ...... .... . ... ., 20 
18 * Terrestrial plants* rhizome erect, plants caespitose .... 19 
18 - Epiphyte, rhizomes elongate, creeping... Sphaeroceronium 
Rachis alate, stipe to 25 cm. long .... .*.. Callistop ter is 
Rachis not alate, stipe ca 4-8 cm* long.... Trichomanes 
20 - Fronds orbicular, minute, less than 1 cm. in diameter........... Gonocormus 
20 - Fronds deltoid or lanceolate, at least 3-4 cm. long #t 21 
Indusium circular, inserted in pinnules, receptacle included...... Mecodium 
indusium tubular, free, receptacle long exserted...... ... Vandenboschia 
22 - Sporangia scattered over the under surface of the leaf blade 
in a uniform layer ... Elaphoglossum 
22 - Sporangia in definite sori ...... 23 
So~i marginal or submarginal..... 24 
Sori dorsal ( i. e . on under surface of leaf)..,............ .. 35 
24 - Indusium present.....25 
24 - Indusia absent; leaves grass-like; sporangia sunken in a 
marginal groove. Vittaria 
- Indusia opening inward .. 29 
- Indusia opening outward. 26 
26 - Sori elongate. Piellia 
26 - Sori circular .. 27 
- Pinnules articulate. Nephrolepis 
- Pinnules not articulate . 28 
.28 - Blade of pinnules developed almost entirely on apical side of 
che midrib......... Lindsaea 
28 - Blade of pinnules developed on both sides of midrib....... . Microlepia 
' 
