The pteridophytes flora of the X Region of Chile is studied and so its presence in 13 forest associations in this zone through the criticizing revision of 75 own and literature vegetation samples.
A catalog of the existing pteridophytes with a brief characterization for each one is given. 70 of the 76 species cited for the region were found, but only 47 of them grow in woody communities. The biological spectrum showed a predominance of hemicryptophytes and epiphytes. It was proved an increase in the number of epiphytic species with the decrease of light in the internal part of the forest. But at higher intensity of light a higher number of terrestrial hemicryptophytes ocurred.
The olivillo and coihue-ulmo forest showed a higher number of ferns although a sharp decrease ocurred in the other woody associations. The forest associations were compared in their pteridophytic floristic similitude through the Ji-square similitude index and a computer analysis. These results are shown in dendrograms that allow to cluster the woody communities in formations assimilable to those described in the literature.