The rangers at Mammoth Cave National Park have many jobs in preserving the natural beauty of the area and a huge part of that conservation is identifying invasive species that harm endemic flora and fauna.
The Mariana Maiden Fern (Macrothelypteris torresiana) is an invasive plant species that has been detected in recent years at Mammoth Cave National Park by the Cumberland Piedmont Inventory and Monitoring Network (CUPN) staff. This invasive species originates in the Asian and African tropics but has spread throughout the Southeastern United States since 1904 and was first reported in Kentucky in 2010. It is not common in the interior plateau ecoregion yet but has been found in the park near the Historic Hill and Cedar Sink since 2020, and its persistent nature is concerning to the park natural resource managers. Left untreated, invasive species can outcompete native species and alter plant communities.
Mariana maiden fern is recognizable by its large, light green, triangular-shaped fronds which arch upwards and then droop towards the ground at the tips. It is bipinnate (has divided leaflets) and has waxy looking stipes (stems) and round sori (structures containing spores on the underside of fronds).
This species reproduces and spreads by dispersing spores, and also via stolons and rhizomes (modified stems that grow horizontal to the soil surface or underground). While the fern is non-toxic to humans and animals, it is never advisable to touch or ingest a plant without absolute certainty on what the plant species is.
Hikers can help park managers document new observations of mariana maiden fern, and any other invasive species, using iNaturalist – a citizen science species reporting and mapping application. The CUPN utilizes iNaturalist to aid in detecting new or significant populations of invasive species.
When observations are posted, park managers are alerted so they are able to manage the species before it becomes a widespread problem.
