Preliminary SEM observations of developing sori of P. aureum revealed several potential areas for future ultrastructural (SEM and TEM) study, including ontogeny of sporangial initials, annulus differentiation, and sport wall development.
Bowen, William R. and Williams, David
"Development of Sporangia in Polypodium aureum var. undulatum: Initial Scanning Electron Microscopial Observations,"
Journal of the Arkansas Academy of Science: Vol. 31
, Article 9.
Available at: http://scholarworks.uark.edu/jaas/vol31/iss1/9