Abstract Detail

Pteridology

Watts, Jacob [1], Watkins, James [2], Moran, Robbin [3].

Hymenasplenium volubile: the first report of hemiepiphytism in the Aspleniaceae.

At the Las Cruces Biological Station in Costa Rica, we studied the gametophytes and sporophytes of Hymenasplenium volubile across an ontogenetic series. The gametophytes of this species have never been described and the ecology of the genus is poorly understood. We made field observations of H. volubile sporophytes and gametophytes and brought specimens back to the lab for microscopic analysis. In the field, sporophytes at each ontogenetic stage were photographed to document the species’ growth habit. We used an existing phylogeny to optimize growth form of New World Hymenasplenium. Young sporophytes were at first fully epiphytic and produce one or two long feeder roots that extend to the soil where they branch profusely. The feeding roots remain in contact with the soil throughout the life of the plant. Thus, H. volubile is a hemiepiphyte. While immature, gametophytes are appressed to the substrate, but as their gametangia mature, their lower margin lifts upward, imparting a shelf-like appearance to the thallus. The thallus attaches to the substrate by branched rhizoids produced along the margin of the thallus in contact with the substrate. Hemiepiphytes are a key link in the evolution of epiphytic ferns and may act as a bridge between the forest floor and the canopy. Our finding is the first report of hemiepiphytism in Aspleniaceae, a large lineage with many epiphytic and terrestrial taxa. This work serves as an important model to understand the evolution of epiphytism in this group specifically and in ferns in general. The majority of our understanding of fern gametophyte biology is derived from laboratory studies. Our efforts represent a fundamental contribution to understanding fern gametophyte ecology in a field setting.

1 - Colgate University, CU Box X 5396 13 Oak Dr., Hamilton, NY, 13346, United States
2 - Colgate University, Department Of Biology, 13 Oak Drive, Hamilton, NY, 13346, United States
3 - New York Botanical Garden, 2900 Southern Blvd., Bronx, NY, 10458-5126, United States

Keywords:
ferns
growth form
hemiepiphyte
Gametophyte biology
ecology.

Presentation Type: Poster
Session: P, Pteridology Posters
Location: Arizona Ballroom/Starr Pass
Date: Monday, July 29th, 2019
Time: 5:30 PM This poster will be presented at 5:30 pm. The Poster Session runs from 5:30 pm to 7:00 pm. Posters with odd poster numbers are presented at 5:30 pm, and posters with even poster numbers are presented at 6:15 pm.
Number: PPT003
Abstract ID:776
Candidate for Awards:None