Gametophyte morphology of Platycerium andinum Baker and Platycerium wandae Racif

Abstract

This paper describes the morphology of the sexual phase and spores of Platycerium andinum and Platycerium wandae. Spores were sown in Thompson's media and the cultures were kept at 24–25 °C, with 12 h light/darkness photoperiod. Developmental phases were fixed in FAA and processed for observation with the scanning electron microscope. Spores of both species are monolete; Vittaria-type germination and Aspidium-type prothallial development were observed. In the phase of development, the gametophytes develop unicellular secretory and as they mature, develop bifurcated or branched pluricellular trichomes, both in the cushion and near the meristematic zone. Adult gametophytes in culture are cordiform-spatulate to cordiform-reniform, most are unisexual and a few are bisexual. Gametangia belong to the leptosporangiate fern type. Archegonial morphology is uniform, with an elongate, thin neck curved toward the base of the gametophyte. Antheridia have a basal cell, an annular cell and an undivided opercular cell. Three hundred days after the spores were sown, sporophytes still had not developed. In both species, some spores germinate inside the sporangial capsule (intra-sporangial germination). We provide new information on morphogenesis in the genus Platycerium.