DISCUSSION
The discovery of Pityrogramma trifoliata in river beds in the xeric belt of the
Andean foothills is a novelty due to the underexplored microhabitat it
inhabited and the stark bareness of the surrounding hills (Fig. 1A). Watkins et
al. (2007) suggested that for terrestrial ferns, soil disturbance is related to
gametophyte establishment success and growth. This also appears to be the
case for our findings, as microsites among the riparian cobble provide shade
and constantly humid soil essential for gametophyte colonization and
development. In turn, these sites are likely highly unstable due to seasonal
fluctuation in river discharge.