In this study we address the phylogenetic relationships within the genus Hymenophyllum. Our sampling includes the segregate monotypic genera Cardiomanes, Serpyllopsis, Rosenstockia, and Hymenoglossum, representatives of the five subgenera proposed for Hymenophyllum by Morton, and of the section Microtrichomanes. Using morphology, cytology, and nucleotide sequences (rbcL, rps4-trnS, rbcL-accD), we obtained a fully resolved topology with several clades well supported. We confirm the monophyly of two clades within the Hymenophyllaceae. Serpyllopsis and Rosenstockia are nested in Hymenophyllum within a derived clade, while Cardiomanes and Hymenoglossum are positioned within a basal grade. Although some of the phylogenetic associations that were previously proposed within Hymenophyllum are supported, many traditionally defined infrageneric taxa are not resolved as monophyletic: subg. Hymenophyllum and Sphaerocionium are paraphyletic, and the broad subg. Mecodium, whose homogeneity had never been questioned, appears polyphyletic.
Of the 225 genera of pteridophytes listed in Kubitzki (1990) there are 131 (58%) genera with no known fungal association, according to the most comprehensive fungal database. The remaining 94 genera are represented by 524 taxa at the species and subspecies level which form about 1848 mainly parasitic interactions with 822 fungal taxa. Around 450 of these interactions are parasitic associations with rust fungi (Uredinales, Basidiomycetes), which are represented by four genera (and two form genera) and around 130 species and subspecies. Fungal synonymies have been resolved as far as possible, however, for this presentation pteridophyte synonymies have only partly been resolved, due to my lack of experience with ferns. This paper examines the taxonomic distribution of fern – fungus interactions in general and the importance of the fern rusts in particular. Examples of interactions are illustrated with the aim of raising awareness among pteridologists and mycologists.
Two populations of Alsophila setosa Kaulf. in secondary semi-deciduous subtropical forest remnants in the State of Rio Grande do Sul, Brazil were studied with attention to frond formation, expansion and senescence rates, as well as to phenology of sporangia formation and spore release, during a 15 month period. Plants of various sizes were marked at a site at Morro Reuter (45 plants) and another at Sapiranga (48 plants) municipalities. The average frond production rates were 5.51 fronds/year at Morro Reuter, and 4.14 fronds/year at Sapiranga. After frost occurrence in early winter, all the exposed young croziers were irreversibly damaged with necrosis of the tissues. A new set of croziers was formed in October (spring), with all the croziers uncoiling almost simultaneously, 84.4% of the specimens in Morro Reuter and 66.7% in Sapiranga presenting one or more croziers in the initial expansion stages. The senescence rates were 6.97 fronds/year at Morro Reuter, and 4.33 fronds/year at Sapiranga. Low temperatures (including the occurrence of frost) and low rainfall during winter coincide with the highest frond senescence, with some plants losing all the fronds. The species presents the capacity to compensate for the occasional loss of all the young fronds in a short period of time, keeping the number of fronds relatively stable at a given development stage. The data indicate ecological limits to the occurrence of this species in Southern Brazil. Spore production occurred only in a few plants, which were at least 2.5m tall. Spore formation is seasonal and maturation gradual to irregular even in a single frond
Archangiopteris somai Hayata and A. itoi Shieh are ferns endemic to Taiwan and are categorized as endangered and critically endangered species respectively. Five fresh stipules were removed from each of 10 sporophytes of A. somai and A. itoi growing in Wu-lai, northern Taiwan. After rinsing in clean water and placing on medium (4:1, soil: peat moss) 50 stipules of each species were cultured at room temperature with 12 hr fluorescent light each day. After one year plantlets were produced by 40% of A. somai stipules and 90 % of A. itoi stipules. Within each species, the mean sprouting rate and sprouting time of stipules from stems of different sizes did not differ significantly. Sprouting and non-sprouting stipules were not significantly different in size. The relationship between average sprouting time and stipule size was very weak (A. somai) or non-existent (A. itoi). The growth of the mother plants from which stipules were stripped was not significantly different from their growth in the previous year, nor did it differ from the growth of control plants. This simple method of propagation from stipules provides an effective means of propagating these two species for horticulture, ex situ conservation and in situ restoration.
Recently discovered frond remains assignable to Osmunda wehrii Miller (Osmundaceae), as well as several new records of Woodwardia (Blechnaceae), and a new onocleoid fern are reported from the Tertiary of western North America. Pinnule morphology of O. wehrii supports the inclusion of this species in Osmunda subgenus Osmunda, as originally proposed by Miller and suggests a close affinity to O. regalis L. and O. japonica Thunb. New occurrences of the Woodwardia aerolata clade are noted for the Late Paleocene of western North Dakota and of a highly reticulate-veined form from the Miocene of western Washington. Re-evaluation of specimens of W. deflexipinna H. Smith (Succor Creek, Miocene) confirms its close affinity to W. virginica J. Smith. A fern with onocleoid anatomy is recognized from the middle Eocene Clarno Nut Beds of Oregon. Together, these examples demonstrate that the presence of critical taxonomic features, even in fragmentary remains, can increase our knowledge of filicalean fern evolution, biogeography and ecology in the Tertiary.
There are many unresolved questions around the loss of viability of pteridophyte spores and the most suitable conditions for long term conservation. The effects of humid and dry conditions, different temperatures, and the short exposure of spores to liquid nitrogen have been occasionally studied by various authors. The work presented here is the first result of a project focussed on long-term conservation of spores of pteridophytes. Using species from different ecological habitats, we show the effects of ultra-freezing, at -80ºC and -196ºC (LN) for six months of storage, on the germination process as well as on the development of the gametophyte until it reaches sexual maturity. We analyze and comment on the results obtained for the final germination percentage and the germination rate, the final percentage of gametophytes that reach the laminate developmental phase, and of gametophytes that attain the sexual phase under the two conditions. All these data are referenced to the initial viability of the samples used as well as to a control of spores stored at room temperature (approx. 25ºC).
The often-stated hypothesis that ferns are attacked less by herbivores than are angiosperms has not been confirmed for terrestrial ferns. Several authors reported for terrestrial ferns and angiosperms the same number of insect pest species, and similar leaf damage of 5-38 percent, depending on species, leaf age, and type of vegetation. We studied five epiphytic species: Pleopeltis crassinervata (Fée) T. Moore, Polypodium furfuraceum Schltdl. & Cham., P. plebeium Schltdl. & Cham., P. polypodioides (L.) Watt, and P. rhodopleuron Kunze , in a Mexican cloud forest to test the hypothesis that epiphytic ferns have less leaf damage than terrestrial ferns. For each species we tagged 14-30 sections of tree branches and marked each fern leaf individually. For each leaf, herbivory was estimated as leaf area loss for each pinna, using a scale of seven damage classes (0%, less than or equal to 10%, ≤25%, ≤50%, ≤75%, ≤100%, 100%), in February 2003 and February 2004. In 2004, we counted the number of marked and unmarked new leaves to calculate leaf life-span. Leaf damage depended strongly on species and leaf life-span, but generally did not differ from the values reported for three terrestrial fern species in the same forest site (5.8- 11.1%). P. furfuraceum and P. rhodopleuron were the least damaged species in both years with 8.4 – 10.7 % mean leaf area loss, while P. plebeium had the highest leaf area losses of 21.2 – 22.0 %. The highest leaf damage in P. plebeium might be a consequence of its longer leaf life-spans of 29.5 ± 3.4 months, while P. rhodopleuron, the least damaged species, had the shortest leaf life-span of less than 12 months.