No abstract

The fern Blechnum sprucei grows in Mesoamerica (Costa Rica) and South America, from Colombia to Bolivia, SE and centre of Brazil, Paraguay and Argentina. It is a distinctive, somewhat vulnerable, mostly orophilous species. Fresh and dry herbarium material was used for this study. Herbarium material for anatomical studies comes from CTES, BA, LP, MA, SI and UC (Holmgren et al.1990). Selected representative specimens are additionally cited after taxonomic treatment of the species. Dry material was restored with aqueous 4:1 butil cellosolve. Pinnae were cleared with aqueous 6% NaOH, then coloured with aqueous 1 % TBO (Gurr 1966). Hand made transverse sections of young and adult stipes, and costae were done in fresh and restored herbarium material. Venation and epidermal patterns were analyzed in basal, apical and medium pinnae, but only the latter were illustrated. The size and density of stomata were measured in medium pinnae from all studied samples, values shown are the average of 25 measures per sample; sizes are expressed as minimum, media and maximum length x width, in µm, and density as minimum, media and maximum number of stomata / mm 2. Spores were studied with SEM, mounted on metal stubs with double sided tape, covered with gold under vacuum and photographed with a Jeol /EO JSM 6360 (15 KV) SEM. Spores were also studied with light microscope, mounted in DePex (DePex mounting medium, Gurr, BDH Laboratory Supplies, Poole BH15 1TD, UK) and measured using an ocular micrometer. Measurements are based on a minimum sample of 100 spores taken from different specimens. Sizes are expressed as the longest equatorial diameter/ polar diameter, in µm. Gametophytes were studied from material collected in the subtropical forest of Tucumán Province, Argentina. Spore samples for cultures were taken from single sporophytes kept dry at room temperature since the date plants were collected. Gametophytes were grown under fluorescent light. Multispore cultures were established on mineral agar. Percentage of germination was recorded for a random sample of 50 spores from each of the two plates, every three days until there was no further increasing. Gametophytes were stained with chloral hydrate acetocarmine. The species has large sporophytes, suberect, scaly rhizomes, and dimorphic fronds with short, scaly stipes and lanceolate to elliptic sterile laminae. The rachises can grow indefinitely as radicant axis that vegetatively multiplicate the plants. Pinnae are lanceolate, herbaceous, with crenate and papillose margins, superficially scaly and hairy, peciolulate, with free, visible veins regularly once furcated near the costa, ending in large, active hydathodes. The broadly elliptic fertile laminae bear distant pinnae, with vegetative tissue reduced to the portion that supports the indusium and the continuous coenosorus; terminal indefinite rachis, not proliferous, may be present.

No abstract

International audienceBlechnaceae is an important leptosporangiate family (9-10 genera, about 250 species). It is monophyletic and distributed mainly in tropical America and Australasia. Among the species 80% belong to Blechnum, a genus with a very complex taxonomy and uncertain internal relationships. In terms of American diversity, the results of morphological studies have arrived at 8 informal groups. Molecular works on this genus are scarce, and there is no information for the majority of American species. The main objective of this work was to evaluate whether the groups proposed to organise the diversity of American of Blechnum are consistent with a molecular analysis. We sequenced 2 chloroplastic regions from species representing all of the groups. In our molecular analysis most of the informal groups were maintained as well supported clades. Only 2 species, B. brasiliense and B. spicant, appear to be isolated from their alleged relatives. Combining our molecular results with previous morphological knowledge, we propose the recognition of 4 lineages: 1) B. serrulatum , 2) B. spicant, and 3) core Blechnum, which represents a large clade that can be divided into core Blechnum I (arborescent species, cordatoids, and B. brasiliense) and core Blechnum II (epiphytic species and herbaceous terrestrials, both monomorphic and dimorphic groups)

No abstract

In the present paper, we provide a revised, comprehensive description of the sporophyte and gametophyte of the swamp fern, Blechnum serrulatum Rich., from neo- and paleotropical localities. External and internal characters of the sporophyte were analysed, including axes, laminae, pinnae, indusia and spores. Intercellular pectic connections of the parenchyma of the rhizomes are reported for the first time. In stipes, cell walls of the aerenchyma tissue contain filamentous protuberances that are composed primarily of cellulose but contain also fatty substances. The morphology of the gametophyte, from spore germination to gametangia formation, is discussed. The taxonomic significance of the characters is considered, especially in regard to the relationship between B. serrulatum and the closely related B. indicum.

Blechnaceae is a worldwide family of leptosporangiate ferns composed of about 250 species. Most of the species in the family were recognised under a single large genus Blechnum until recently, when a new classification proposed the recognition of 24 genera. Given this new systematics of Blechnaceae, which largely resolves the genus‐level relationships in the family, there is a need for phylogenetic research to investigate relationships within the majority of the newly proposed genera. In this paper, we unravel the phylogenetic relationships and the historical biogeography of the species of Lomaridium, a genus including most of the hemiepiphytic species in the Blechnaceae. Our sampling includes 11 species, which represents 85% of the diversity in the genus and which covers the entire geographic distribution of the group. We constructed two datasets with three plastid markers: one for phylogenetic analyses (maximum likelihood, Bayesian inference) with four outgroups from phylogenetically close genera (Brainea, Lomaria, Sadleria, Woodwardi); and a second for molecular dating and historical biogeographic analyses that included a larger set of outgroups so that we could accurately reconstruct ancestral events at the base of Lomaridium, under different models. We are able to recognize four highly supported lineages: L. contiguum and the L. schottii, L. attenuatum, and L. fragile clades. Our results date the origin of Lomaridium at some point during the Paleocene epoch, and the most likely geographic area for its origin is Australia plus tropical Central and South America. Several dispersal events are inferred, all of which are most likely long‐distance dispersal events. From Australia, we infer a first dispersal event that brought the ancestor of the extant species L. contiguum to New Caledonia. In Central and South America, Lomaridium continued to diversify and colonized additional areas, including the Caribbean (L. binervatum), some Pacific islands (L. schottii), and Africa and Madagascar. While our goal in the current study was not to estimate the biogeographic or diversification history of all Blechnaceae, our analyses do suggest that the early history of the family was complex biogeographically, with extensive long‐distance dispersal events. Lomaridium exemplifies this high dispersal capacity, as a genus with only a modest number of species that have reached far‐flung regions of the globe via numerous long‐distance dispersal events.

The gametophyte of Argyroschosma nivea was studied, mainly focusing in its morphological development, and in the apogamous production of sporophytes. Some observations on the spores were also made. As far as it is known, this is the second species of the genus whose gametophytes are studied. The germination pattern followed the Vittaria type. The subsequent developmental processes followed the Ceratopteris type. Some of the gametophytes reached an adult stage with a cordate, symmetric shape, but most of them developed as irregular, lobed prothalli. The sporophyte emerged from the anterior part of the prothallus, without formation of gametangia. First, a cell became active and originated a proliferating area of small cells. From this area, long glandular hairs were formed followed by a projected conical cluster of cells. The cluster elongated into a sporophytic structure and its apex became progressively spatulate and finally trilobulate, with marginal, glandular hairs, stomata and tracheids continuously produced. This sporophyte secreted granules of white farina from its beginnings. The production of farina in the sporophyte but not in the gametophyte could help to support the idea of the segregation of this species from its traditional location in Notholaena to Argyrochosma, as farinose gametophytes seem to be a synapomorphy of the notholenoids, group that includes Notholaena but not Argyroschoma.