Reproductive expression of cheilanthoid ferns (Pteridaceae) from South America

The characteristics of the reproductive stage of eight neotropical cheilanthoid ferns species, Cheilanthes buchtienii, C. hieronymi, C. obducta, C. pilosa, C. sarmientoi, Gaga marginata, Myriopteris myriophylla, and M. notholaenoides are presented. The study includes quantitative information on spores, germination, morphological development, and sexual expression. In vitro cultures were performed and analyzed with light microscopy and scanning electron. The results showed that the species differ in the number of spores by sporangium, being 32 and/or 64. All species present a rapid gametophytic development. The gametophytes of the filamentous stage are short, consisting of 3-5-cells, or long, consisting of more than five cells. The adult gametophytes are orbicular, cordate, cordate-elongated, and shortly ribbon-like, mostly lacking indument. Most species are protanders when young; adult laminar gametophytes are unisexual, bisexual and/or vegetative. Archegonia have a neck of 4-6-cells and antheridia have a basal cell, an annular cell and opercular cell; antheridial dehiscence occurs through a pore in the opercular cell. In some species gametophytes produce vegetative buds. Reproduction is sexual or apogamic.