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Indiana University Studies 
four hundred miles of Plains that are now barren of oak. 
Between the Rocky Mountain oak of northern Colorado and 
the westernmost extension of the eastern Quercus macrocarpa 
in northwestern Nebraska is a stretch of fully two hundred 
miles. In the Black Hills of the South Dakota-Wyoming 
boundary, this same eastern oak comes into contact with the 
Rocky Mountain Quercus Gambelii, but this could at most 
FIGS. 11-12. PHYLOGENETIC ORIGINS IN PHILONIX AND 
ATRUSCA 
