1993/02/01 by Wilson A. Taylor · 1 citation
Agricultural and Biological Sciences · #Fern and Epiphyte Biology #Plant Diversity and Evolution #Plant and animal studies
paper · doi:10.1002/j.1537-2197.1993.tb13785.x
openalex publication_date 1993/02/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/05/21
In Selaginella , megaspore wall ultrastructure (unit morphology and arrangement) is correlated with taxonomic position. In some Pennsylvanian lycopods there is a correlation with dispersal strategy. This study was designed to assess any correlation between habitat preference and wall ultrastructure in Isoetes. Except for a few minor structural correlations, wall ultrastructure appears to be constant in terrestrial, amphibious, and aquatic species of Isoetes. Several distinct sizes of megaspores occur in some megasporangia and correspond to 1) full‐size megaspores with siliceous coatings, 2) small megaspores with siliceous coatings, and 3) full‐size megaspores without siliceous coatings. The uniformity in wall ultrastructure within modem Isoetes together with the lack of uniformity of fossil isoetalean megaspore wall ultrastructure suggest that the modem species of Isoetes are closely related.