Diversity of ferns and lycophytes from Reserva Natural Punta Lara, Buenos Aires, Argentina. Punta Lara Natural Reserve shelters the relict of the Southernmost riparian forest in the world, where the flora is threatened by the anthropic expansion and by the introduction of exotic species. In this area the ferns and lycophytes grow in particular environments as marshland, grassland and marginal forest. The aim of this work was to evaluate the diversity of ferns and lycophytes that inhabit in Punta Lara Natural Reserve. Field trips were conducted from 2006 to 2009 and local herbaria and specific bibliography were also revised. As a result of our study twenty four taxa of ferns and lycophytes were recognized. Their habit was mainly terrestrial (70%), fewer aquatic (17%) and epiphytic (13%). Five native taxa were scarcely recorded whereas two native species previously documented were not found. We assume that the main threats on ferns and lycophytes populations in Punta Lara Reserve are: removal for comercialization, invasion by exotic species and climatic fluctuations (drought periods). Keys for taxa identification are given and strategies for the conservation of threatened taxa are proposed. Rev. Biol. Trop. 59 (3): 1037-1046. Epub 2011 September 01.

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Tlie spores of the following genera of Polypodiaceae growing in northwest Argentina were analyzed: Campyloneurum, Microgramma, Pecluma, Phlebodium, Pleopeltis and Polypodium. The study involved analyses of herbarium material using light microscopy and scanning electron microscopy. The spores are monolete, 40-90 [im in major equatorial diameter, eliptic to oblong in polar view and plane to concave-convex in equatorial view. The exospore ranges from 2-5 |im thick, is apparently double-layered, with a verrucate or tuberculate surface that is usually perforated. The perispore ranges from 0.3-1 [am thick, is apparently single-layered, attached to the exospore, perforated, and generally smooth or in some cases micro-ornamented. Most of the taxa analyzed have globules on the surface. These are single or associated in masses and irregularly distributed. Characteristics such as size, shape and exospore and perispore sculpture allow us to differentiate among some of the genera as well as recognize species groups. Microgramma, Campyloneurum, Pecluma, Pleopeltis and Polypodium have verrucate spores whereas those of Phlebodium are tuberculate.

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