Glacier National Park encompasses over one million acres in the mountains of northwestern Montana, along the United States–Canada border. Our survey of online databases indicates that the earliest extant fern and lycophyte collections from this area were taken by Robert S. Williams in 1892. In the summer of 1919, Paul C. Standley, a botanist with the United States National Museum, conducted a survey of the flora of the newly created Park and recorded 39 species of ferns and lycophytes. In 2002, a revised flora for the Park by Peter Lesica increased this number to 61. Here we summarize 130 years of collections-based research on the ferns and lycophytes of Glacier National Park, documenting how our understanding of the flora has changed through time. In the summer of 2019, the lead author conducted a field survey to relocate as many ferns and lycophytes as possible within park boundaries. In parallel, we scoured herbarium online portals and databases for high-resolution digitized specimen images to confirm or refute historical vouchers of ferns and lycophytes collected from the Park. In a few cases, specimen loans were requested from herbaria to confirm our determinations. The results from our combined field and online herbarium studies are presented here. Of the 61 taxa recognized by Lesica in 2002, we were able to confirm all but seven. In sum, we recognize here a total of 71 fern and lycophyte taxa for the Park. Most previously unreported taxa belong to Botrychium, a genus that has seen a flurry of recent taxonomic work by co-author Farrar and collaborators. These new data are presented here together with updated nomenclature and discussion to provide a current taxonomic account of the fourteen fern and lycophyte families known to occur in Glacier National Park. We anticipate this study will provide a useful foundation for further investigations in the Park.

We present an update to our knowledge of the taxonomically challenging Cyathea multiflora-group. Several taxa can be reinstated and newly described thanks to extensive field studies in Colombia and bordering countries. Easily overlooked characters like minute hairs, laminar squamules, and size of indusia correlate with distinct physiognomies in the field. Cyathea multiflora in the strict sense is almost restricted to Mesoamerica, just reaching into the Colombian Darién region. We observe a geographic overlap of several species especially in the Darién-Chocó region (Cyathea hildegardis sp. nov., C. pinnula, C. pinnuloides sp. nov., C. retanae) and two wider-ranging species extending from Mesoamerica into the Andes (C. acutidens, C. pinnula). The reinstated C. columbiana and newly recognized C. uregoana sp. nov. and C. prosopioides sp. nov. are restricted to the Chocó, including the Ecuadorean Esmeraldas region. Frequently found in the northern Colombian Cordillera central is C. paisa sp. nov., which is intermediate between C. pinnuloides of the Darién-Chocó region and C. lindigii, a relatively large species widespread in the Cordillera Oriental and the eastern Andean slopes south to Bolivia. We retain C. acutidens and C. leucolepismata as distinct species that can also be readily distinguished in the field by their appearance and the shape of the entire leaves but can be difficult to differentiate as fragmentary specimens. Cyathea mariposana sp. nov., a trunkless species presumably more closely related to C. squamulosa, is described from Panama. Cyathea retanae is reported from Colombia. A lectotype is chosen for C. columbiana. All relevant species are illustrated and incorporated in a diagnostic key.

Plants are characterized by their marked plasticity and ability to alter their functional biology to partition ecological niches. However, there are limits to functional trait exploration especially in complex and stressful habitats. Highly specialized traits may control a species ability to explore within and across habitats. Such may be especially true of epiphytes, whose array of unique traits may constrain their ability to cross establish in epiphytic and terrestrial habitats. In the case of ferns, there are few reported examples of species that can grow across these habitats with regularity. However, this study reports and explores species that exhibit great ecological flexibility growing across a wide range of habitats and growth forms. Specifically, we examine species that grow as 1) terrestrially rooted and epiphytic individuals, 2) nest and non-nest-forming epiphytes; and nest-forming terrestrially rooted individuals, and 3) species that grow as terrestrial, epiphytic, and epipetric individuals. We use natural abundance foliar stable isotope ratios (SIR) of N¹⁵ and C¹³, and %N, to explore intraspecific variation in mineral nutrition and water relations across and within niches. Our results reveal the 1) unreported ability of some species to grow across the epiphytic/terrestrial divide, 2) surprising ability of some species to explore these habitats with little to no shift in functional traits; 3) a potentially new function for the nest in nest-forming epiphytes. Finally, our work highlights the need to consider intraspecific trait variation more carefully when studying ferns that occur across a wide range of habitats.