Hill’s Oak: The Taxonomy and Dynamics of a Western Great Lakes Endemic

into the history of our landscape, flora, and vegetation. Oaks have been among the dominant trees of eastern North American forests and woodlands for approximately 10,000 years (Abrams 1992). Between 8,000 and 3,000 years ago, oaks spread to distributions close to those we observe today (Webb 1981). The landscape between the prairies of the Great Plains and the eastern deciduous forest had by that time settled into a broad transition zone in which prairie, woodland, and savanna shifted with the dynamics of climate and fire (Anderson and Bowles 1999). Some oak species in this region could persist below ground for decades as their shoots were regularly burned to the ground, growing to maturity only when a break in fire frequency allowed their stump sprouts to grow (Kline 1997). The oldest oaks still growing have borne witness to fires, changes in forest structure and composition, and substantial anthropogenic landscape changes. These old oaks sustain large numbers of mammals, birds, and insects. Blue jays, squirrels, and, previously, passenger pigeons have eaten, hoarded, and dispersed acorns in vast quantities (Johnson and Adkisson 1986; Keator and Bazell 1998; Price 1999, ch. 1), and civilization rests in part on the structural and nutritional properties of oaks (Logan 2005). It is hard for a North American naturalist to imagine a landscape without oaks. At the same time, oaks are remarkable for their ability to stump botanists. Even where there are only a few species to choose from, we often struggle to put a name on oaks in the field, and annotations on many herbarium specimens capture decades of disagreement. Oaks are notoHill’s Oak: The Taxonomy and Dynamics of a Western Great Lakes Endemic