Gametophyte development and reproduction of Argyrochosma nivea (Pteridaceae)

Abstract

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.

A Gompertz regression model for fern spores germination

“…Sw.) and as toxic species for cattle (Pteridium aquilinum), with strong economic impact (Prada, 2004). In recent years we have conducted several studies on germinating fern spores: developmental observations (Gabriel y Galán & al., 2008a;Gabriel y Galán & al., 2008b;Gabriel y Galán & Prada, 2009;Gabriel y Galán & Prada, 2010a;Gabriel y Galán & Prada, 2010b;Migliaro & Gabriel y Galán, 2012), physiological studies (Gabriel y Galán & Prada, 2010c), reproductive biology reviews (Prada & al., 2008;Gabriel y Galán, 2010;Gabriel y Galán, 2011), ecological analyses (Gabriel y Galan & al., 2011 and taxonomical/phylogenetical studies (Gabriel y Galán & Prada, 2012) of both the spore and/or the fern gametophyte that arise when the spore germinates. Even when physiological and ecological aspects of fern spore germination have been extensively studied (Weinberg & Voeller, 1969;Lloyd & Klekowski, 1970;Raghavan, 1989;Sheffield, 1996;Gabriel y Galán & Prada, 2010c) surprisingly this is the only group of plants where germination has never been statistically modelled.…”

Comparative study on the gametophyte morphology and development of three paramo species of Jamesonia (Pteridaceae, Polypodiopsida)

“…(Gabriel y Galán and Prada 2009) and Argyrochosma nivea (Poir.) Windham (Gabriel y Galán 2011), 40 days Cheilanthes pilosa Goldm. (Gabriel y Galán and Prada 2010) and 45 days Pteris incompleta Cav.…”

“…Sexual organs detected in J. imbricata and J. rotundifolia are of the normal type defined for the leptosporangiate ferns (Nayar and Kaur 1971). However, apogamy is a very common phenomenon in the Pteridaceae (Nayar and Kaur 1971, Gabriel y Galán 2011), so it is desirable to observe in the future if the gametophytes of Jamesonia reproduce in a sexual way or not, especially J. scammaniae , which produced no gametangia in our cultures.…”

“…However, these potentially powerful characters have often been ignored. Recently, in the search of morphological synapomorphies to support a molecular phylogenetic hypothesis, gametophyte features have been used to help segregating some genera of the Pteridaceae (Sanchez‐Baracaldo 2004a,b, Schuettpelz et al 2007, Gabriel y Galán 2011). In this context, we wanted to contribute new information on the gametophytes of some species of Jamesonia , a genus that have not been studied in this respect.…”

Protagonismo de los alumnos en el aprendizaje: Una experiencia en el primer curso de medicina

“…En algunos seminarios también hubo una breve (máximo de 15 minutos) presentación por el profesor de algunos conceptos y objetivos concretos de ciertas tareas. Con este fin, se comentaron los poema El desahuciado, de Gabriel y Galán [12], y Llega el litio, de Goytisolo [13], así como una breve narración referida a la actuación de un médico rural contenida en Un hombre afortunado, de John Berger [14]. Los materiales orientativos aportados para seminarios y ABP se han extraído de obras generales publicadas [15][16][17][18][19][20][21][22] Escrito en el cual un autor desarrolla sus ideas, utilizando un lenguaje adecuado para que pueda entenderlo el destinatario Redacción de un ensayo original sobre metodología de la ciencia, aspectos sociales de la ciencia o la profesión médica Tutoría grupal 6 Sesiones de discusión no programada, centradas en la orientación para la preparación de las exposiciones y trabajos de los alumnos y, en menor medida, en la resolución de dudas generales de la marcha del curso…”