Slow return of the annulus towards its almost initial configuration after relaxation. The launch of the spores is not visible due to the comparably slow recording speed of 1000 fps. The sporangium was gripped with tweezers (MOV, 20 fps, 120 x 128 pixels, 642 KB).
Poppinga S, Haushahn T, Warnke M, Masselter T, Speck T
CC BY 4.0
<a rel="nofollow" class="external text" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4596474/bin/pone.0138495.s013.mov">S12 Video</a> from <cite style="font-style:normal">Poppinga S, Haushahn T, Warnke M, Masselter T, Speck T (2015). "<a rel="nofollow" class="external text" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4596474">Sporangium Exposure and Spore Release in the Peruvian Maidenhair Fern (Adiantum peruvianum, Pteridaceae)</a>". <i>PLOS ONE</i>. <a href="https://en.wikipedia.org/wiki/Digital_object_identifier" class="extiw" title="w:Digital object identifier">DOI</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1371/journal.pone.0138495">10.1371/journal.pone.0138495</a>. <a href="https://en.wikipedia.org/wiki/PMID" class="extiw" title="w:PMID">PMID</a> <a rel="nofollow" class="external text" href="https://www.ncbi.nlm.nih.gov/pubmed/26444002">26444002</a>. <a href="https://en.wikipedia.org/wiki/PubMed_Central" class="extiw" title="w:PubMed Central">PMC</a>: <a rel="nofollow" class="external text" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4596474">4596474</a>.</cite>