Physiological and morphological properties of a deciduous, perennial fern (Onoclea sensibilis) and three wintergreen, perennial ferns (Polystichum acrostichoides, Polypodium virginianum, and Dryopteris intermedia) were examined using leaf fluorescence, chlorophyll a:b ratios, total chlorophyll content, water potential, and leaf edge to surface area ratios. Onoclea sensibilis differed significantly from the wintergreen ferns in morphology and physiology for almost every parameter measured. Interspecific differences were also observed within the wintergreen group. Dryopteris intermedia differed most within the wintergreen group and showed more similarity in physiology to O. sensibilis. Dryopteris intermedia was found occupying the same high-light, higher soil moisture habitat as O. sensibilis, which may indicate that inherent leaf morphology, physiological characteristics, and a wintergreen or perennial life cycle, play important roles in determining habitat preference.

A previously unrecognized interspecific hybrid in the fern genus Polypodium is described from collections made at a single remote locality in central Arizona. Originally identified as P. glycyrrhiza, this sterile nothotaxon is easily distinguished from other members of the genus and is here named Polypodium ×aztecum Windham & Yatsk. The hybrid is tetraploid, exhibiting ca 37 bivalents and 74 univalents at diakinesis. Based on geographic proximity and shared morphological traits, we conclude that P. hesperium is one of the parents of the new taxon. Assuming that the hybrid is more or less intermediate between P. hesperium and a second parental taxon, we attempt to identify the missing parent. The most likely candidate is P. calirhiza, a species of Oregon, California, and Mexico that has not been documented from Arizona. However, we cannot rule out the possibility that the missing parent is an as yet unidentified member of the P. plesiosorum complex from Mexico.

Chloroplast DNA (cpDNA) atpB-rbcL intergenic spacers of individuals of Alsophila podophylla, collected from eight relict populations distributed in Hainan and Guangdong Province, southern China, were sequenced. Sequence sizes were 726 or 727bp. Base composition had a high A T content of 62.67–63.00%. Sequences were assessed as evolutionarily neutral (Tajima's criterion D = −0.80683, P > 0.10 and Fu and Li's test D* = 1.42648, P > 0.05; F* = 0.76638, P > 0.10). Eight haplotypes were identified based on a statistical parsimony algorithm. A high level of haplotype diversity (h = 0.618) and a low nucleotide diversity (Dij = 0.00208) were detected in A. podophylla. Populations from Hainan shared common haplotypes with those from Guangdong. A network and a NJ tree constructed from cpDNA haplotypes both suggested a close genetic relationship among populations distributed in Hainan and Guangdong. Observed F_ST (=0.10537), gene flow Nm (=2.12), AMOVA (Only 0.49% of variation was partitioned among regions, P = 0.09), and DNA divergence data consistently indicated that no geographical differentiation occured at the interregional level. Geographic isolation has not yet resulted in population differentiations within A. podophylla populations in Hainan and Guangdong. Phylogeographical patterns of atpB-rbcL haplotypes demonstrate a ‘star-like’ feature, which means that populations of A. podophylla have experienced population expansion, and, since then there has been insufficient time to form a more complicated population structure. The majority of haplotypes coalesced near the tip of the NJ tree, indicating recent coalescence events as well. Moreover, a demographic signature of population expansion was detected by mismatch distribution analysis of atpB-rbcL sequences of A. podophylla.

Pneumatopteris pendens, a new endemic Hawaiian species related to P. sandwicensis, is described.