Ontogenia del esporangio y esporogénesis del licopodio Huperzia brevifolia (Lycopodiaceae) de las altas montañas de Colombia

Abstract

Sporangia ontogeny and sporogenesis of the lycopodium Huperzia brevifolia (Lycopodiaceae) from the high mountains of Colombia. Huperzia brevifolia is one of the dominant species of the genus Huperzia living in paramos and superparamos from the Colombian Andes. A detailed study of the sporangium's ontogeny and sporogenesis was carried out using specimens collected at 4200m above sea level, in Parque Natural Nacional El Cocuy, Colombia. Small pieces of caulinar axis bearing sporangia were fixed, dehydrated, paraffin embedded, sectioned in a rotatory microtome, and stained using the common Safranin O-Fast Green technique; handmade cross sections were also made, stained with aqueous Toluidine Blue (TBO). The sporangia develops basipetally, a condition that allows observation of all the developmental stages taking place throughout the caulinar axis of adult plants. Each sporangium originates from a group of epidermal cells, axilar to the microphylls. These cells undergo active mitosis, and produce new external and internal cellular groups. The sporangium wall and the tapetum originate from the external group of cells, while the internal cellular group leads to the sporogenous tissue. Meiosis occur in the sporocytes and produce simultaneous types tetrads, each one giving rise four trilete spores, with foveolate ornamentation. During the sporangium ripening, the outermost layer of the wall develops anticlinally, and inner periclinal thickenings and the innermost one perform as a secretory tapetum, which persists until the spores are completely mature. All other cellular layers colapse. Rev. Biol. Trop. 57 (4): 1141-1152. Epub 2009 December 01.

Morfología y anatomía de ejes caulinares, licofilos y esporangios de Phlegmariurus phylicifolius: un aporte a la sistemática de las Lycopodiaceae neotropicales

“…Los esporangios comienzan a formarse, a partir de un grupo de células epidérmicas localizadas en la axila de los primordios de licofilos en el ápice caulinar. A medida que el eje caulinar crece van madurando los esporangios de posición más basal, mientras que otros nuevos se van formando del ápice, por lo que el desarrollo de los esporangios es basípeto, fenómeno observado en otras Lycopodiaceae (Rolleri, 1972;Sérsic, 1983;Øllgard 1987;Uehara & Kurita, 1991;Rincón Barón, Gélvez Landazábal, Forero Ballesteros, Arrieta Prieto & Hleap, 2009) y que corresponde a una sinapomorfía de la familia. Durante la ontogenia esporangial en P. phylicifolius, se observa que inicialmente la pared que delimita el lóculo presenta tres o cuatro capas celulares; mientras que Rolleri (1972) observó, en diferentes especies de Lycopodium, que la pared del esporangio estaba formada inicialmente por seis a siete capas celulares que se reduce a cuatro durante el desarrollo, y Rincón Barón et al (2009) encontraron que en P. brevifolius la pared del esporangio poseía cuatro a cinco capas de células.…”