In order to attempt an identification of the various large grass
pollen encountered, the long axis of each grain and the pore diameter
(including annulus) were measured, and the ratio between the two
plotted. Barghoorn, Wolfe, and Clisby (1954) have suggested that this
ratio can be used to supplement size measurements in attempting to
identify fossil pollen of the tribe Maydeae. However, one can not
compare directly the size data from the LoDaisKa fossils with the data
from modern pollen assembled by Barghoorn, Wolfe, and Clisby (l.c.).
Christensen (1945) has shown that not only do recent and fossil grains
of the same species differ in size (depending partly upon the type
of sediment in which the pollen is preserved), but also, different
methods of preparation greatly affect the size, often differentially
with respect to fossil and modern pollen. The recent pollen measured
by Barghoorn, Wolfe, and Clisby (l.c.) was prepared by acetolysis
and mounted in glycerine jelly. By comparing the size of modern
_Corylus avellana_ pollen prepared and mounted in this manner (ca.
28, Christensen, 1945) with the size of fossil _Corylus avellana_
pollen from a variety of sediment types prepared and mounted by the
technique used in the present investigation (ca. 24, S. T. Andersen,
pers. comm.), one can arrive at a factor (7/6) by which the size of the
fossils can be multiplied in order to compare more directly with the
data presented by Barghoorn, Wolfe, and Clisby (l.c.). It should be
emphasized that such an absolute comparison is dangerous, because there
is no way of determining precisely how the environment of preservation
at LoDaisKa has affected the pollen, and there is no guarantee
that size changes of Corylus and Gramineae pollen are absolutely
proportional.
For each grass grain both the long axis measurement and the pore axis
ratio are tabulated in the results below. Only fully expanded grains
were measured.