Resumen

RAMIREZ, Ma. del Rosario  y  PEREZ-GARCIA, Blanca. Fase gametofítica del helecho Microgramma nitida (Polypodiaceae). Rev. biol. trop [online]. 1998, vol.46, n.3, pp.587-593. ISSN 0034-7744.

The development of the gametophytic phase of Microgramma nitida is described based on spore samples that was obtained of fertil specimens gathered on Veracruz State, Mexico. The spore sowing density was 40 spores/cm2 ; it is characterized by Vittaria-type germination of the spore, a germinal filament of six cells; young gametophytes are naked, spathulated and later are transformed in cordate-elongated adult gametophytes with wavy borders; marginal, superficial capitated, unicellular hairs; the meristematic cell is wedge-shaped and is quickly replaced by a pluricellular meristem. The antheridia and archegonia are of the usual Polypodiaceae s. str.type. Prothallial development is thus of the Drynaria-type. The first leaf of the sporophyte appeared eight months after spore sowing. The leaf is spathulated, with smooth borders and the margin has a row of cells without chlorophyll; bifurcated and pluricellular hairs; anomocytic stomata; the epidermic cells of the sporophyte have wavy walls on upper and lower surfaces.

Palabras clave : Gametophyte; México; Microgramma; morphogenesis; Polypodiaceae s. str.