SMITH, SELENA Y.* and RUTH A. STOCKEY. Department of Biological Sciences, University of Alberta, Edmonton Alberta, T6G 2E9 Canada. - Further investigations of Keratosperma allenbyensis (Araceae) from the Middle Eocene Princeton chert (Allenby Formation) of British Columbia.
Keratosperma allenbyensis seeds from the Middle Eocene Allenby
Formation near Princeton, British Columbia were reexamined from over
200 new specimens. Anatomical characters have shown their affinities
to seeds of Araceae, Subfamily Lasioideae. The seeds were reexamined
using the cellulose acetate peel technique modified for hydrofluoric
acid. Seeds are campylotropous with three rows of spiny ridges on the
integument. Idioblasts that contained raphides are found scattered in
the outer integument. The micropylar end of the seed shows an epistase
and a thin micropylar cover that was easily displaced at the time of
germination. At the chalazal end of the seed a prominent hypostase and
podium are present. Endosperm tissue and monocotoledonary embryos are
present in some but in most specimens these tissues have been invaded
by fungi. Anatomical comparisons with the extant lasioids
Cyrtosperma ferox Linden et N. E. Br. and Urospatha
sagittifolia (Rodsch.) Schott were made using paraffin and cryo
embedding and sectioning techniques. A reconstruction of the fossil
seed was made from serial sections allowing the fossils to be compared
to extant taxa based on external morphology. Affinities of
Keratosperma were originally believed to be with
Cyrtosperma from tropical southeast Asia. While shape is most
similar to seeds of Urospatha from Central and South America,
integumentary zones are distinctly different making these seeds
unique. Keratosperma allenbyensis are the oldest known lasioid
seeds in the fossil record and represent an extinct araceous lasioid
taxon.
Key words: Araceae, Eocene, Keratosperma, seeds