|This study documents the presence of white oaks in the middle Miocene
of central Washington state, based on the presence of characteristic morphological
and developmental features of the acorns. These acorns have a highly reduced
perianth, and are thus thought to demonstrate the presence of annual fruit
habit by the middle Miocene. They also contain insect damage patterns,
galls and fungi that are the subject of a later study.
|Borgardt, S. J., and K. B. Pigg. 1999. Petrified
acorns from the Miocene of North America and their significance to the
evolution of Quercus L. (Fagaceae). Amer. J. Bot. 86:307-325.
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