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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.

ABSTRACT. Morphology, characterization, and geographical distribution of Blechnum cordatum (Blechnaceae-Pteridophyta). Specimens of Blechnum cordatum from localities of its large geographical area were analized. The species grows in Mesoamerica, Antillas and South America, from Venezuela and Colombia to Bolivia, SE and centre of Brazil, Paraguay, Argentina, centre and S of Chile, and Juan Fernández Islands. Blechnum cordatum is a tolerant, not vulnerable species, with large sporophytes; erect, scaly rhizomes; dimorphic fronds with scaly stipes and axes; lanceolate sterile laminae with lanceolate to oblong, coriaceae, finely denticulate to serrate, superficially scaly and hairy, attached by costa (peciolulate) pinnae, with cuneate- truncate to subcordate or auriculate bases, and narrowly lanceolate fertile laminae with vegetative tissue of pinnae reduced to the portion which support the undulate to erose indusia and continuous coenosorus. Veins are free, simple, geminate and furcate, the latter ramdomly dividing at different distances from the costa, all ending in large, active hydathodes. Aerophores, located only at the base of pinnae, may be absent. Spores have a cristate-reticulate perispore with filiform, ramified processes, and a smooth to granulate exospore. Based on this study, a new description of Blechnum cordatum, and its taxonomy is presented, along with comments on affinities with other neotropical and paleotropical species of the genus.Key words. Blechnaceae, Blechnum cordatum, morphology, taxonomy, palynology, geographical distribution.RESUMEN. Morfología, caracterización y distribución geográfica de Blechnum cordatum (Blechnaceae-Pteridophyta). Blechnum cordatum fue estudiado en especímenes de numerosas localidades de su extensa área de distribución. Crece en Mesoamérica, Antillas, Sudamérica, desde Venezuela y Colombia a Bolivia, SE y centro de Brasil, Paraguay, Argentina, centro y S de Chile e islas de Juan Fernández. Es una especie poco vulnerable, tolerante, con esporófitos grandes, rizomas a oblongas con pinnas coriáceas, lanceolado-oblongas, finamente denticuladas a aserradas, superficialmente escamosas y pilosas, unidas al raquis por la costa (pecioluladas), con bases cuneado- truncadas a subcordadas o auriculadas y láminas fértiles estrechamente lanceoladas con el tejido vegetativo de las pinnas reducido a la porción de la lámina que lleva el cenosoro continuo e indusio ondulado a eroso. Las venas son simples, geminadas y bifurcadas al azar a distancias variables de la costa y terminan en grandes hidatodos activos, sobresalientes o más o menos planos. Los aeróforos, presentes sólo en la base de las pinnas, pueden faltar. Las esporas son monoletas, con perisporio crestado-reticulado que lleva procesos filiformes y exosporio subliso a granulado. La especie se describe e ilustra en detalle, se actualiza su taxonomía y se comentan sus afinidades con otras especies neotropicales y paleotropicales del género.Palabras clave. Blechnaceae, Blechnum cordatum, morfología, taxonomía, palinología, distribución geográfica.

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Este trabajo presenta un análisis de las fitocenosis y listas actualizadas de la flora vascular (con excepción de las Poaceae) de dos humedales permanentes, La Balandra y la Isla Santiago, y de varios humedales temporarios (arroyo Rodríguez, arroyo El Gato, y otros) de las zonas costeras del Río de La Plata (provincia de Buenos Aires, Argentina). El estudio se basó en el trabajo de campo y el seguimiento estacional de las comunidades silvestres entre los años 2005 y 2011, con un registro de 126 taxones de flora vascular determinados en ese lapso. Las Dicotiledóneas representan el grupo dominante en ambos humedales, seguido en número por las Monocotiledóneas y escasos representantes de pteridófitos. En el humedal de La Balandra se registraron 102 especies de plantas vasculares que incluyen 33 familias de dicotiledóneas (53 géneros), 17 de monocotiledóneas (22 géneros) y 5 de pteridófitos (5 géneros), mientras que en el humedal de Isla Santiago se registraron un total de 116 especies pertenecientes a 36 familias de dicotiledóneas (64 géneros), 16 de monocotiledóneas (25 géneros) y 6 de pteridófitos (7 géneros). Las fitocenosis de los humedales permanentes y transitorios se compararon con la biodiversidad registrada en áreas costeras protegidas, como la Reserva Provincial de Punta Lara. La biodiversidad de la Isla Santiago es claramente mayor que la de La Balandra y está seriamente amenazada por acción antropogénica y por el progreso de la zona como área habitacional. La biodiversidad en los humedales transitorios es la más disminuida en relación con la flora prístina y su vulnerabilidad se incrementa cada año. This paper presents an analysis of phytocoenoses and updated lists of the vascular flora (with the exception of Poaceae) of two permanent wetlands, La Balandra and Isla Santiago, and several temporary wetlands (Arroyo Rodríguez, Arroyo El Gato, and others) in the coastal areas of the Rio de La Plata (Buenos Aires Province, Argentina). The study was based on field work and monitoring seasonal wild communities between years 2005 and 2011, with 126 vascular plant taxa identify during the period. Dicotyledons represent the dominant group in both wetlands, followed in number by Monocotyledons and a few Pteridophyta representatives. In the wetland of La Balandra 102 species of vascular plants, including 33 families of Dicotyledons (53 genera), 17 of Monocotyledons (22 genera) and 5 belonging to Pteridophyta (5 genera) were recorded, while in Isla Santiago wetland a total of 116 species were collected belonging to 36 Dicotyledon families (64 genera), 16 to Monocotyledons (25 genera) and 6 to Pteridophyta (7 genus). The phytocoenoses of permanent and temporary wetlands were compared with recorded biodiversity in protected coastal areas, such as the Reserva Provincial de Punta Lara. The biodiversity of Isla Santiago is clearly larger than La Balandra, and is seriously threatened by anthropogenic activity and progress in the zone as a residential area. The temporary wetlands biodiversity is the most diminished in rela...