Dr. Jeffrey M. Osborn
Dean of the School of Science and Professor of Biology
The College of New Jersey
Phipps, C. J., J. M. Osborn, and R. A. Stockey. 1995. Pinus pollen cones from the Middle Eocene
Princeton chert (Allenby Formation) of British Columbia, Canada.
International Journal of Plant
Sciences 156: 117-124.
Anatomically preserved pollen cones are described from the Middle Eocene Princeton chert of British Columbia,
Canada. Cones are ellipsoidal, range from 2.8-6.9 mm in length, 1.6-3.5 mm in diameter, and are often subtended
by scale leaves. Cone axes contain longitudinally oriented, cortical resin canals and 14-18 vascular bundles.
Microsporophylls are helically arranged, each bearing two abaxial pollen sacs, many containing pollen grains.
Grains are bisaccate and monosulcate, ranging from 50-70 µm in length and 27-43 µm in width. Proximally,
the corpus is rugulate with a tectate-alveolate infrastructure. Sacci have a well-defined endoreticulum and
an external ornamentation that is psilate to scabrate. Variations in cone size, cone anatomy, and pollen
morphology indicate that several developmental stages are preserved. The large number of cones present in the
chert, especially those representing short-lived ontogenetic stages, and the preservational quality of the cones
support depositional interpretations for a rapid burial and preservation. These factors also indicate that the
pollen cone producing plants occupied a marginal position in close proximity to the lacustrine environment.
Four species of Pinus, based on woody twigs, dwarf shoots, leaves, and ovulate cones, are presently known from
the Princeton chert. The association of these pollen cones with P. similkameenensis leaves and P.
ovulate cones indicates possible taxonomic affinities among these species. The Princeton chert specimens are the
oldest Pinus pollen cones to be described and are the first in the genus for which fossil pollen ultrastructure
has been described.
Pinus, Princeton chert, Middle Eocene, pollen, saccate morphology, ultrastructure