35

THE line delimiting the western margin of this region and the eastern margin of Region 18 is the line of contact between outcropping Navarro and Midway geological formations.' The former is a marl, a limy (calcareous) clay; the latter a mixture of sand and clay, the clay red or yellow, or of some other color. As usual, the actual line of contact between the two regions is exceedingly sinuous with mottes of timber standing as islands in the prairie and with embayments of prairie lying both between peninsular timber strips and as "lakes" well within the timbered region wherever marl deposits become locally of sufficient thickness materially to diminish the absorption and increase the surface evaporation rate of the soil. Such grassland inclusions in the Oak-Hickory Forest were prized by pioneers because of their higher fertility and because of the fact that it was unnecessary to clear away timber and cultivate stumpy "new ground" for several years before a cleared field became really profitable. Community names throughout the region still commemorate the occurrence of these virgin bits of prairie. Roark's Prairie, Crabb's Prairie, Pine Prairie, Cline's Prairie, Round Prairie, and others in my home county of Walker are examples that can be duplicated in any other county of the region. Some such prairie fragments are found even in Region 17. In fact a part of those enumerated lie within that region, the line separating 16 and 17 passing through Walker County.

That portion of the region lying southwest of the Brazos River is somewhat unique in that it contains two plants of outstanding interest: the official Texas state flower (Lupines sub-carnosus) and Drummond's Phlox (Phlox drummondii). The fact that Lupinus sub-carnosus is the State Flower rather than the more showy and more widely distributed Lupinus texensis, seems to be due to an inadvertant error on the part of those sponsoring the Bluebonnet. In drawing up the joint resolution designating an official flower, the committee specified sub-carnosus, thinking, doubtless, that texensis