Dr. Jeffrey M. Osborn
Dean of the School of Science and Professor of Biology
The College of New Jersey
Osborn, J. M. and T. N. Taylor. 1993. Pollen morphology and ultrastructure of the Corystospermales: Permineralized
in situ grains from the Triassic of Antarctica. Review of Palaeobotany and Palynology 79: 205-219.
Corystosperms, represented by Dicroidium leaves and Pteruchus-like pollen organs, are major components of the
Early-Middle Triassic silicified flora from the Fremouw Formation of Antarctica. The micromorphology and
ultrastructure of the in situ pollen contained within these organs are described. Pollen sacs of varying
ontogenetic ages have been isolated. Mature grains are monosulcate and bisaccate, with large, crescent-shaped
eusacci. The exine is relatively thick in the cappa region and thins toward the distal sulcus; surface
ornamentation is psilate. In medial positions of the proximal wall, the exine is homogeneous but becomes
tectate-alveolate in more lateral regions of the cappa. The alveolar units extend into the sacci forming an
endoreticulum; however, the endoreticulations are discontinuous and only attach to the outer walls of the sacci.
A wedge-shaped unit, where the sacci attach to the corpus, characterizes both the proximal and distal poles.
The sulcus is broad, extends the entire width of each grain, and is longitudinally flanked by elevated lips.
The structural features of these grains are discussed with respect to other fossil and extant saccate pollen.
The grains are systematically compared with those of other bisaccate pollen-producing plants with which the
Corystospermales have been suggested to be closely related, including Glossopteridales, Caytoniales, and
angiosperms (Lactoridaceae). The permineralized in situ grains are also compared with other compressed
species known at the ultrastructural level and with morphologically similar dispersed palynomorphs known from
Corystospermales, Pteruchus, pollen, Antarctica, ultrastructure, seed fern,