A fern from the French Pyrenees—×Cystocarpium roskamianum—is a recently formed intergeneric hybrid between parental lineages that diverged from each other approximately 60 million years ago (mya; 95% highest posterior density: 40.2–76.2 mya). This is an extraordinarily deep hybridization event, roughly akin to an elephant hybridizing with a manatee or a human with a lemur. In the context of other reported deep hybrids, this finding suggests that populations of ferns, and other plants with abiotically mediated fertilization, may evolve reproductive incompatibilities more slowly, perhaps because they lack many of the premating isolation mechanisms that characterize most other groups of organisms. This conclusion implies that major features of Earth's biodiversity—such as the relatively small number of species of ferns compared to those of angiosperms—may be, in part, an indirect by-product of this slower "speciation clock" rather than a direct consequence of adaptive innovations by the more diverse lineages.

Here we present the first nuclear phylogeny for Cystopteridaceae (Polypodiales), using the single-copy locus gapCp "short". This phylogeny corroborates broad results from plastid data in demonstrating strong support for the monophyly of the family's three genera-Cystopteris, Acystopteris, and Gymnocarpium-and of the major groups within Cystopteris (C. montana, the sudetica and bulbifera clades, and the C. fragilis complex). In addition, it confirms the rampant hybridization (allopolyploidy) that has long been suspected within both Cystopteris and Gymnocarpium. In some cases, these data provide the first DNA-sequence-based evidence for previous hypotheses of polyploid species origins (such as the cosmopolitan G. dryopteris being an allotetraploid derivative of the diploids G. appalachianum and G. disjunctum). Most of the allopolyploids, however, have no formal taxonomic names. This pattern is particularly strong within the C. fragilis complex, where our results imply that the eight included accessions of "C. fragilis" represent at least six distinct allopolyploid taxa.

A First Record of Polypodium saximontanum for the Flora of Montana.— Recent fieldwork in western Montana has yielded a new locality for Polypodium saximontanum Windham, a species previously known only from scattered populations in northern New Mexico, Colorado, eastern Wyoming, and western South Dakota. Polypodium saximontanum is an allotetraploid member of the Polypodium vulgare reticulate complex, derived originally through hybridization between the diploid species Polypodium amorphum Suksd. and Polypodium sibiricum Sipliv. (Windham, Contr. Univ. Michigan Herb. 19:31–61. 1993; Haufler et al., Polypodium. Pp. 315–323 in Flora of North America North of Mexico, vol. 2. Oxford University Press, New York. 1993). The collection of P. saximontanum from the Bitterroot Mountains in Ravalli County, Montana, greatly expands the geographic range for this species, occurring approximately 800 kilometers to the northwest of the closest known population in the Laramie Range of Wyoming. As is characteristic of P. saximontanum, the new specimen was obtained from a population growing on granitic rock, but at elevations lower than previously reported (1237 m versus 1800–3000 m; Windham 1993; Haufler et al. 1993). Initially, the Montana collection was identified as Polypodium hesperium Maxon, a relatively common species in the mountains of western Montana (pers. obs.) and the only Polypodium species reported in the Checklist of Montana Vascular Plants (S. Mincemoyer, Checklist of Montana Vascular Plants. Montana Natural Heritage Program, Helena, Montana. 2012). Morphologically similar to P. saximontanum, P. hesperium is an allotetraploid derived from the diploids P. amorphum and Polypodium glycyrrhiza D.C. Eaton. Microscopic inspection of the sori (10–403 magnification) revealed the presence of glandular sporangiasters among the sporangia, a character diagnostic of P. saximontanum, but absent from P. hesperium (Windham 1993; Haufler et al. 1993). Spores removed from the sporangia were well formed, with an average length of 67 mm, consistent with the size class of other tetraploids in the complex. Analysis of biparentally inherited gapCp nuclear sequence data revealed that the Montana collection contains alleles inherited from both P. amorphum and P. sibiricum (Sigel et al., unpubl.), further supporting its identification as P. saximontanum.

Premise of the study: Not all ferns grow in moist, shaded habitats; some lineages thrive in exposed, seasonally dry environments. Notholaenids are a clade of xeric-adapted ferns commonly characterized by the presence of a waxy exudate, called farina, on the undersides of their leaves. Although some other lineages of cheilanthoid ferns also have farinose sporophytes, previous studies suggested that notholaenids are unique in also producing farina on their gametophytes. For this reason, consistent farina expression across life cycle phases has been proposed as a potential synapomorphy for the genus Notholaena. Recent phylogenetic studies have shown two species with nonfarinose sporophytes to be nested within Notholaena, with a third nonfarinose species well supported as sister to all other notholaenids. This finding raises the question: are the gametophytes of these three species farinose like those of their close relatives, or are they glabrous, consistent with their sporophytes?Methods: We sowed spores of a diversity of cheilanthoid ferns onto culture media to observe and document whether their gametophytes produced farina. To place these species within a phylogenetic context, we extracted genomic DNA, then amplified and sequenced three plastid loci. The aligned data were analyzed using maximum likelihood to generate a phylogenetic tree.Key results: Here we show that notholaenids lacking sporophytic farina also lack farina in the gametophytic phase, and notholaenids with sporophytic farina always display gametophytic farina (with a single exception). Outgroup taxa never displayed gametophytic farina, regardless of whether they displayed farina on their sporophytes.Conclusions: Notholaenids are unique among ferns in consistently expressing farina across both phases of the life cycle.