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Spores of bracken fern, Pteridium aquilinum were sown in medium with and without agar. No clear trend emerged for germination, but in 14 days, significantly more plants passed from the filamentous to two-dimensional state on agar-solidified medium than in liquid shake-flasks. Spores of Pteridium aquilinum, Athyrium filix-femina, Dryopteris expansa and Anemia phyllitidis were sown in media containing sucrose. Percentage germination of all four species was significantly enhanced by the inclusion of sucrose.
The value of preserving wintergreen fronds into the spring by forest understory fern species is unknown. In this study, net photosynthetic rates and nitrogen and phosphorus contents were monitored in a population of Dryopteris intermedia throughout a spring season to explore potential photosynthetic and retranslocational benefits of wintergreen fronds. Net photosynthesis occurred throughout the study indicating a potential for movement of fixed carbon from wintergreen fronds to other parts of the plant. Nitrogen and phosphorus content in the old fronds did not change through spring, thus no evidence for net retranslocation of these nutrients from wintergreen fronds to the rest of the plant was obtained. Maintenance of the wintergreen fronds may simply increase retention time and thus nutrient use efficiency of limiting nutrients. Other possible benefits of wintergreen fronds exist and should be investigated.
Nucleotide sequences of the chloroplast-encoded rbcL gene were determined for Loxoscaphe thecifera and Actiniopteris radiata and used in maximum parsimony cladistic analyses to determine their phylogenetic positions in the context of a broad range of advanced fern taxa. Loxoscaphe nested firmly within the Aspleniaceae, and Actiniopteris was placed with Onychium in the Pteridaceae. To help resolve conflicting contemporary treatments that either subsume Loxoscaphe species within Asplenium or segregate them as an independent genus, the rbcL sequence of L. thecifera was subjected to a more focused analysis involving all rbcL sequences available to represent the taxonomic diversity of Aspleniaceae. Loxoscaphe thecifera was sister to Asplenium griffithianumprolongatum, robustly and surprisingly nested within the clade of Asplenium species recognized as Asplenium section Thamnopteris, a group accepted by some as the segregate genus Neottopteris. These results indicate that there is presently no phylogenetic justification for accepting Loxoscaphe as a genus independent of Asplenium. Similarly Actiniopteris radiata, recently moved from the cheilanthoid to the taenitidoid group of Pteridaceae, was subjected to a more focused analysis in the context of an expanded set of cheilanthoid and taenitidoid species that included the first use of an rbcL sequence from the genus Anogramma and newly sequenced species of Onychium and Pteris. Actiniopteris is robustly grouped with two Onychium species in a clade sister to traditional taenitidoids and deeply separated from the cheilanthoids, supporting affinities previously suggested by spore morphology.
The development and morphology of the sexual phase of Pseudocolysis bradeorum (Polypodiaceae) are described from material collected in Finca La Selva, near Puerto Viejo, Province of Heredia, Costa Rica. Spores were sown in Thompson medium with agar (25 Petri dishes) and germinated after seven days; the germination pattern was Gleichenia-type and the prothallial development Drynaria-type. Gametangia were typical of homosporous leptosporangiate ferns. Sporophytes appeared after seven months of culture. The sexual phase of this species shares many morphological characteristics with Old and New World species of Polypodiaceae. There is a tendency for vegetative propagation with Pseudocolysis gametophytes.