Fern Fuiora or NEBRASKA—I 11 
is known as the Hat creek basin. The soil is largely 
clays and marls, absorbs little water,and readily erodes. 
- This unstable soil receives little rain and much summer 
heat, hence there is little or no vegetation. 
In favorable situations in the cafions are found: Botry- 
chum virginianum, Filix fragilis, Woodsia oregana, 
Equisetum arvense, Equiselum laevigatum,and Equisetum 
robustum. 
GENERAL DIsTRIBUTION. 
The fern flora in Nebraska is represented by 17 genera 
and 26 species. Of these, Botrychium neglectum, Os- 
munda regalis, Osmunda claytoniana, Cryptogramma 
acrostichoides, Dryopteris cristata, Notholaena dealbata, 
and Isoetes melanopoda are quite rare, being known 
from but one locality for each. Cheilanthes feei, Dryop- 
teris spinulosa, and Azolla caroliniana are known from 
two localities for each. Pellaea atropurpurea and 
Athyrium filix-foemina have been collected in three or 
four localities. Adiantum pedatum, a common eastern 
fern but which ranges across the continent, occurs in 
Nebraska only in the southeastern quarter. Botrychium 
virginianum, Filix fragilis, Dryopteris thelypteris, Onoclea 
sensibilis, Marsilea vestita, Equisetum arvense, Equisetun 
laevigatum and Equisetum robustum are the only species 
that are frequent to common and widely distributed over 
the state. Pteris aquilina, the nearly cosmopolitan spe- 
cies, does not occur, neither does Polypodium vulgare nor 
Camptosorus rhizophyllus. There are no Lycopodiums. 
The nearly cosmopolitan species, Athyrium filix-foemina, 
is found in Nebraska only in two or three favorable lo- 
calities. 
SUMMARY AND CONCLUSIONS 
From this it is readily seen that the fern flora of Ne- 
braska is conspicuous for its poor development. The 
reasons for this paucity may be due to the effects or 
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