Standard molar enthalpies of formation and phase changes of Tetra-N-phenylbenzidine and 4,4′-Bis (N-carbazolyl)-1,1′-biphenyl

Journal of Thermal Analysis and Calorimetry - The values of the standard molar energies of combustion of Tetra-N-phenylbenzidine and 4,4′-Bis(N-carbazolyl)-1,1′-biphenyl in solid phase...     

Developmental gametophyte morphology of seven species of Thelypteris subg. Cyclosorus (Thelypteridaceae)

The morphogenesis of the sexual phase of seven species of Thelypteris subg. Cyclosorus (Thelypteridaceae) is described and compared. Spores of all species are monolete, ellipsoid and have positive photoblastism. They have Vittaria-type germination, germinal filaments are short and uniseriate, and Aspidium-type development. Adult gametophytes are spatulate-cordiform, and have wide wings with numerous glandular, marginal and superficial hairs. Antheridia have a narrow or widened basal cell, an undivided annular cell, and an opercular cell; antherozoids are liberated through three mechanisms. Archegonia have short necks and four triangular cells on the neck's mouth. The sporophyte's first leaf is lobed, with open dichotomous veins, glandular hairs similar to those of the gametophyte, and anomocytic stomata. Differences observed between the studied species are: spore size; ornamentation of the perispore; germination and emergence periods; size of hairs; developmental period of gametangia; and antherozoid liberation mechanisms through total detachment of the operculum, partial detachment of the operculum, and development of an apical pore through tearing of the operculum. These taxonomically valuable characters, combined with the sporophyte characteristics, can be useful tools in the identification of the species studied to the subg. Cyclosorus.     

Gametophyte morphology of Platycerium andinum Baker and Platycerium wandae Racif

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.