A cursory examination of the deciduous forest of eastern North America, at intervals from its center (14) in the Ohio River basin westward, discloses changes in the structure of the forest characterized chiefly by a reduction in number of species and in the abundance and size of the component trees. Beyond the Mississippi river in Iowa and eastern Nebraska the forest flora is concentrated chiefly along streams flowing diagonally southeastward. Bordering these streams the deciduous forest extends into the prairie
