SiS.S 
MlS 
KS* 
The Ferns have been classified by their fruit, which consists 
powder like spores in a case ( sporangium ). Tire sporangia are often clustered 
dots ( sori ), and these are sometimes covered by a thin skin ( indusium ). 
of minute one-celled 
into round or oblong 
Polypodium and Phegopteris, 
sori round and uncovered. 
Pteris and Adiaxtum, sporangia 
covered by the edge of leaf. 
Woodwardia, sori oblong, paral- 
lel to ribs. 
Asplenium, sori oblong, oblique 
to ribs, and opening inwards. 
Dicksoxia, indusium cup-shaped, 
supported by a tooth of the 
leaf. 
Woodsia, indusium hood-like, 
covering the sporangia. 
Cystopteris, indusium fastened 
behind sori, opening from the 
centre. 
Aspidium, indusium kidney or 
shield shaped, fastened at the 
middle, 
openin 
g all round. 
Ox t oclea, 
fertile 
on separate 
contracted fronds, sporangia 
covered 
leaves. 
with 
deformed 
Osmunda 
and 
Botrychium, 
sporangia uncovered, and 
separate. 
Lygodium, indusium scale-like, 
covering the sporangia. 
Ophioglossum, sporangia un- 
covered, and connected. 
