Revision of the argentine species of the genus Adiantum L. (Pteridaceae, Pteridophyta)

Adiantum comprises seventeen taxa in Argentina: Adiantum chilense Kaulf., A. chilense var. scabrum (Kaulf.) Hicken, A. chilense var. sulphureum (Hook.) Giudice comb. nov., A. digitatum C. Presl ex Hook., A. filiforme Gardn., A. latifolium Lam., A. lorentzii Hieron., A. macrophyllum Sw., A. orbignyanum Mett. ex Kuhn, A. pectinatum Kuntze ex Ettingh., A. pseudotinctum Hieron., A. raddianum C. Presl, A. serratodentatum Willd., A. tetraphyllum Willd., A. thalictroides Willd. ex Schltdl., A. thalictroides f. bottini Giudice & Nieto y A. thalictroides var. hirsutum (Hook. & Grev.) de la Sota. A dichotomus key, descriptions, synonym and geographic distribution are also given.El género Adiantum L. está representado en Argentina por diecisiete taxones: Adiantum chilense Kaulf., A. chilense var. scabrum (Kaulf.) Hicken, A. chilense var. sulphureum (Hook) Giudice comb. nov., A. digitatum C. Presl ex Hook., A. filiforme Gardn., A. latifolium Lam., A. lorentzii Hieron., A. macrophyllum Sw., A. orbignyanum Mett. ex Kuhn, A. pectinatum Kuntze ex Ettingh., A. pseudotinctum Hieron., A. raddianum C. Presl, A. serrato-dentatum Willd., A. tetraphyllum Willd., A. thalictroides Willd. ex Schltdl., A. thalictroides f. bottini Giudice & Nieto y A. thalictroides var. hirsutum (Hook. & Grev.) de la Sota. Se presenta en este trabajo una clave para la determinación de los taxones, así como las descripciones, sinonimias y distribuciones geográficas correspondientes.Facultad de Ciencias Naturales y Muse

Adiantum L.

Fil: Giudice, Gabriela Elena. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Cátedra de Morfología Vegetal; Argentin

Spore morphology and sporoderm ultrastructure in Adiantopsis Fée (Pteridaceae-Pteridophyta) from Argentina

The aim of this study is to analyse, describe and compare the spores of the two Adiantopsis species that grow in Argentina, A. chlorophylla (Sw.) Fée and A. radiata (L.) Fée. The study used herbarium material observed with light microscopy (LM), scanning electron microscopes (SEM) and transmission electron microscopes (TEM). The spores of both species are trilete with an echinate surface. The exospore is smooth, two-layered in section; both layers with different thickness and contrast. Depending on the plane of sectioning, channels are seen running through the exospore and in the apertural region. The perispore strongly contrasted when seen with TEM, is two-layered and bears ornamentation. The two layers have different thickness and structure. The inner layer P1 is the thickest layer and has three strata, which form the sculptural elements. The outer layer P2 covers all the surfaces of P1. Two levels of ornamentation are clearly distinguished: a basal level composed of fused ridges, and an upper level composed of echinae. The spores of A. chlorophylla are triangular-globose in polar view, with convex sides, 25 - 50 μm in equatorial diameter and have more ornamental processes per surface unit than the spores of A. radiata. The spores of A. radiata are triangular in polar view and 30 - 40 μm in equatorial diameter. Size and ornamentation help to establish differences at species level, and together with the exomorphological characteristics of the sporophyte, contribute to the systematics of this genus.Facultad de Ciencias Naturales y Muse

Spore morphology and ultrastructure of Cyathea (Cyatheaceae, Pteridophyta) species from southern South America

Spore sculpture and wall structure of eight Cyathea (Cyatheaceae) species from southern South America were studied using light microscopy (LM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques. Two layers, i.e. an inner and an outer layer, were observed in the perispore. The inner layer has two strata: the inner stratum is attached to the exospore and composed of rodlets tangentially oriented to the spore surface and randomly intermixed; the outer stratum consists of a three-dimensional network of rodlets with either free or fused distal edges forming spinules. The outer layer is thin, darkly contrasted and covers the rodlets. In most cases, the exospore has two layers and a pitted surface. In Cyathea atrovirens, the exospore surface is smooth, while in C. delgadii and C. myriotricha it is verrucate. The homogeneity of perispore features within the genus Cyathea is evident, while exospore features are heterogeneous. The exospore has different kinds of surface-structures that are of potential interest for assessing evolutionary trends within the group.Facultad de Ciencias Naturales y Muse

Record of Thelypteris decurtata (Link) de la Sota ssp. platensis (Weath.) de la Sota in Punta Lara (Buenos Aires) Natural Reserve: a contribution to the conservation of native ferns with restricted distribution

Se da a conocer el registro de Thelypteris decurtata ssp. platensis en la Reserva Natural Punta Lara (Provincia de Buenos Aires). Este helecho tiene una distribución restringida, es endémico de Argentina y Uruguay y se lo encuentra asociado a cursos de agua o zonas inundables. Hasta el momento se contaba con citas de colecciones de más de 50 años y en distintas zonas cercanas a la Reserva. Se destaca la importancia de la selva marginal, que representa el extremo austral de la selva en galería asociada a los ríos mesopotámicos y que constituye un refugio natural para la flora nativa. Se describe e ilustra el material registrado y se proponen estrategias para su conservación.This paper discloses the presence of Thelypteris decurtata ssp. platensis in Punta Lara (Buenos Aires) Natural Reserve. This fern has a restricted distribution since it is endemic of Argentina and Uruguay, and grows near watercourses and in flood zones. So far there were collections dating more than 50 years, in different areas around the Reserve. We highlights the importance of the marginal forest, which represents the southern end of the gallery forest associated with the mesopotamian rivers, and it is a natural haven for native flora stands. Description and illustrations of the registered taxon are given and strategies for its conservation are proposed.Fil: Giudice, Gabriela Elena. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo; ArgentinaFil: Ramos Giacosa, Juan Pablo. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Luna, María Luján. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo; Argentina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; Argentin

Spore wall ultrastructure in Anogramma species (Pteridaceae) from Argentina

The sporoderm ultrastructure of Anogramma Link species, which grow in Argentina, was studied using scanning and transmission electron microscopy. The species A. chaerophylla (Desv.) Link and A. lorentzii (Hieron.) Diels were studied with TEM for the first time. The spores of both species have a sculptured, apparently two-layered exospore. The perispore is uniformly thickened on the whole surface: in A. chaerophylla it is three-layered, while, in A. lorentzii it is single-layered with a complex structure. Spherules are present on the perispore surface or incorporated into the structure of A. chaerophylla while, globules exist on and within the perispore in A. lorentzii. The sporoderm ultrastructure in these two species was compared with other cingulate genera within the Pteridaceae. The characteristics found in this work, with respect to spore wall structure and general morphology, suggest that these characters may differentiate species within genus.Facultad de Ciencias Naturales y Muse

Spore wall ultrastructure in Anogramma species (Pteridaceae) from Argentina

The sporoderm ultrastructure of Anogramma Link species, which grow in Argentina, was studied using scanning and transmission electron microscopy. The species A. chaerophylla (Desv.) Link and A. lorentzii (Hieron.) Diels were studied with TEM for the first time. The spores of both species have a sculptured, apparently two-layered exospore. The perispore is uniformly thickened on the whole surface: in A. chaerophylla it is three-layered, while, in A. lorentzii it is single-layered with a complex structure. Spherules are present on the perispore surface or incorporated into the structure of A. chaerophylla while, globules exist on and within the perispore in A. lorentzii. The sporoderm ultrastructure in these two species was compared with other cingulate genera within the Pteridaceae. The characteristics found in this work, with respect to spore wall structure and general morphology, suggest that these characters may differentiate species within genus.Facultad de Ciencias Naturales y Muse

Anogramma lorentzii

Fil: Giudice, Gabriela Elena. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Cátedra de Morfología Vegetal; ArgentinaFil: Luna, María Luján. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Cátedra de Morfología Vegetal; Argentin