Photosynthetic gas exchange was measured in situ with either the adaxial or abaxial leaf surface illuminated on vertical, horizontal, and angled leaves of Asplenium nidus and vertical leaves of Ophioderma pendula, two epiphytic ferns in a subtropical rain forest in northeastern Taiwan. Leaves for gas exchange measurements were selected to ensure a diversity of different exposures of the two leaf surfaces to direct sunlight. For most leaves of both species, photosynthetic rates were higher when the side of the leaf that typically received more direct insolation was illuminated during the gas exchange measurement. Higher rates of net CO₂ uptake when one side of the leaf was illuminated, relative to rates when the opposite side was illuminated, were attributable to a greater biochemical capacity for photosynthesis, not to greater stomatal conductances. Based on the results of this study, the photosynthetic capacity of the two sides of the leaves of epiphytic ferns, for the most part, reflects the degree of exposure of each side of the leaf to direct sunlight, as has been found in similar studies of terrestrial taxa.

Two separate experiments were conducted to determine the influence of temperature (15, 23 and 35°C) and various light intensities, ranging from 80 to near 700 µmol/m²/s on selected physiological responses of salvinia (Salvinia minima). This was an attempt to determine the distribution range of this plant as influenced by these selected environmental factors. The first experiment was carried out for 14 days under controlled environments, with a light intensity of 120 µmol/m²/s and 14 h photoperiod. Plant growth was the highest at 23 and 35°C, in comparison to those grown at 15°C. The chlorophyll concentration was less influenced by the temperature than by the growth; however, carotenoid concentration at 35°C was significantly higher than those obtained from the plant grown at 15°C. Salvinia acclimation to cold temperature possibly included an increase in athocyanin and soluble sugar concentrations. The second experiment was carried out under greenhouse conditions, 25–27°C and various light intensities ranging between 80 to near 700 µmol/m²/s in order to determine the light saturation curve. Salvinia was shown to have a wide range of acclimation ability to various light intensities ranging from 80 to near 700 µmol/m²/s. This study should be helpful for determining the ecological distribution of salvinia.

Fern species and growth form diversity peak in tropical rainforests. In such forests, ferns often play important ecological roles. However the distribution and diversity patterns of different growth forms (i.e., epiphytic vs. terrestrial ferns) have not been broadly quantified. We compared the distribution and diversity patterns of epiphytic pteridophytes on the trunks of six individuals of the emergent canopy tree species Hyeronima alchorneoides (Euphorbiaceae) to those of terrestrial species at La Selva Biological Station in Heredia province, Costa Rica. A total of 21 species of epiphytic and 20 terrestrial ferns was recorded, with only one species found as an epiphyte and as a terrestrial species. Epiphytic species also exhibited increasing species diversity with increasing trunk height. Epiphytic species exhibited predictable patterns of distribution along the trunk and were easily grouped into high-trunk, low trunk, or bimodal categories. In terms of percent cover and number of species, simple-leaved ferns dominated the epiphytic growth form, 13 of 21 species, whereas ferns with compound or dissected leaves dominated the hemi-epiphytic and terrestrial floras with 20 of 20 species. These results indicate that there are significant functional differences in the ecology of epiphytic and terrestrial ferns and that reciprocal establishment is difficult and extremely rare.

Microbial communities, associated with terrestrial mosses (Bryopsida) and the rhizosphere of agricultural and natural occurring seed plants, have been rather extensively examined; but less is known about associations with seedless vascular plants, including ferns. The New York fern (Thelypteris noveboracensis), typically found within deciduous forests, occurs in locally extensive stands in North America extending from northeastern Canada to southeastern U.S.A. Soil samples were obtained in autumn (2007) and early summer (2008) within a plot of T. noveboracensis in the understory of deciduous trees in the forest reserve at Torrey Cliff, NY to document the rhizosphere (root-associated) density of commonly occurring heterotrophic eukaryotic microbes (protozoa), including microflagellates, naked amoebae and testate amoebae. The ranges in densities (number/g soil dry weight) are as follows: microflagellates (6.5 × 10⁶–1.3 × 10⁸), naked amoebae (1.8 × 10³–4.0 × 10⁶) and testate amoebae (ca. 400). Very few active ciliates were observed. This is the first report of microbial communities associated with the rhizosphere of ferns and provides a step toward a more complete documentation of protozoa associated with plant communities. Some comparative data of protozoa associated with mosses and seed plants are also presented.

The present investigation is a detailed study of the vasculature of the rhizome of four species of Polypodium (P. cambricum, P. fauriei, P. interjectum, and P. sibricum). The vascular architecture of the rhizomes of the Polypodium species studied denotes a line of reduction and simplification of characters. The characteristic nature of the association of branches with leaves in the species of Polypodium studied seems to be significant. Vascular morphology of the rhizome of Polypodium does not support a close relationship with Goniophlebium as has previously been hypothesized. However, more extensive study of Polypodium is needed to arrive at any definite conclusion.

Isoetes maxima from eastern Brazil is described as a new species. This taxon differs from other fully aquatic species in South America by a combination of its overall size, leaf coloration, finely tapering subulae, and megaspore morphology.

Polyphlebium borbonicum is newly recorded in Central and South America and Easternmost Polynesia (Marquesas and Society Islands). It has been misidentified as P. diaphanum and as P. endlicherianum in the New World and in the Pacific, respectively. Polyphlebium borbonicum is distinguishable from true P. diaphanum by broader blade segments, and from true P. endlicherianum by the absence of a marginal elongate cell row of the lamina.

With the purpose of providing a basis for programs of sustainable management in the conservation of this endangered species, this paper presents morphological aspects on the gametophyte development of Dicksonia sellowiana (Dicksoniaceae) by light microscopy and scanning electron microscopy. Dicksonia sellowiana spores were germinated in Morh's nutrient solution modified by Dyer (1979) under a 16-hour photoperiod at 23 ± 2°C. To determine the best substrate for gametophyte and sporophyte development, 30 days after spore sowing filamentous gametophytes were transferred to different substrates: soil rich in organic matter; coxim (coconut fiber); sterilized typic hapludult soil (distroferric red nitosoil); and sterilized typic hapludult soil (distroferric red nitosoil) with the addition of organic compost. The best system for D. sellowiana growth was the red soil with the addition of compost. Fifteen days after spore sowing in mineral solution, gametophytes were filamentous. Some had attained laminar morphology and had established an oblique cell division, giving rise to the obconic cell. Laminar gametophytes were observed 30 days after spore sowing and cordate gametophytes were observed after 45 days. Mature cordate gametophytes were observed after 80–90 days. After 245 days 84.67% of gametophytes had produced sporophytes in sterilized red soil with the addition of organic compost. In typic hapludult soil, without the additional termophilic compost, sporophyte formation was delayed (development after 180 days). When gametophytes were transplanted to soil rich in organic matter they did not develop and in the “coxim” substrate, which is a substitute for the “xaxim” substrate, only filamentous gametophytes were observed at the end of the study.

Gametophyte development in Arthromeris himalayensis was studied and found to be of “Drynaria type”. Germination occurred 9–10 days after sowing of spores. Some prothalli showed an initial archegonial phase, which persisted throughout gametophyte development and the antheridial phase developed on separate thalli a few days later and persisted throughout the life span of the gametophytes. This type of development of sex organs may be considered as a variant new type from the previously reported types by earlier authors. This variant type is described here as “type H”. This type of gametangial development on separate prothalli is an indication of adaptation for out breeding.

Spores are commonly used to start in vitro culture of ferns. Numerous methods for spore surface sterilization and sowing have been developed, but spore loss and contamination are still problematic. To overcome these problems, an efficient method for sterilizing and sowing spores was established. Through this method, contamination and loss of spores is minimized, and can be sown in adjustable, even densities.