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A taxonomic study of the Pteridophyta of the Hawaiian Islands— 
WINIFRED J. ROBINSON 
(WITH PLATES 18-20) 
The following paper is a partial result of the study of ferns 
and fern allies of the Pacific Islands, which was begun several 
years ago under the direction of the late Professor Lucien M. 
Underwood, whose design was to combine the regional taxonomic 
studies of a number of workers in a comprehensive report which 
should include ecological and morphological features as well. To 
the writer was assigned the taxonomic study of the Hawaiian 
fern flora. 
The Hawaiian Islands lie at the crossroads of the Pacific, 
latitude 18° 55/-22° 15’ north, longitude 154° 50’-160° 30’ west, 
more than two thousand miles from San Francisco and about the 
same distance from the nearest islands to the southwest. They 
are farther from the mainland than any other group of islands 
of the same extent; and while a geodetic map shows that they 
have arisen by volcanic action through a fissure in the earth’s 
Siena which extends from northwest to southeast, there is nothing 
. indicate that they were ever connected by a chain of islands 
with Japan, and there is very little in common in the floras of 
Japan and Hawaii. Hence their isolation must have been as 
complete through the ages as it is now. With the exception of 
“oral limestone along the shore and a little sandstone and sedi- 
Seem at rock, the soil is uniformly of basaltic origin. Kauai, 
8eologically the oldest island of the group, about 2,000 m. high 
at its highest point, is most eroded and deserves its name of the 
8arden island. Hawaii, with two snow-capped peaks, Mauna Kea 
— each nearly 5,000 m. high, and with its active 
be me : auea, is still in the making. The ridges are steep 
saat rg at narrow in all the islands. Asa Rule the northeast 
oc les ae wis and 1s covered with rain forest, while the southwest 
1S arid because of the direction of the prevailing winds. 
