=Distribution.=--Massachusetts, Indiana, south to Florida, and west to Oklahoma and Texas. In Indiana it is confined to the southwestern part of the State. In our area it is found on the crest of ridges in the knob area where it is generally associated with black, and black jack oaks, hence in our poorest and thinnest soils. West of the knob area it takes up different habitats. From Vigo County southward it is found on sand ridges associated with black and black jack oaks. West of the knob area it is frequently found in black oak woods and in Warrick County about two miles southwest of Tennyson it is a frequent tree in the Little Pigeon Creek bottoms which are a hard light clay soil. Here it is associated with pin oak and cork elm (_Ulmus alata_). In the Lower Wabash Valley, especially in Point Township of Posey County in the hard clay of this area it is a frequent to a common tree, associated with Spanish, pin, swamp, white and shingle oaks, and sweet gum. In this area it grows to be a large tree. This species has been reported for Hamilton County by Wilson, but I regard this reference a wrong identification which will relieve Hamilton County of the reputation of having "post oak" land. It was reported, also, by Gorby for Miami County. Since Gorby's list is wholly unreliable, it is best to drop this reference. Higley and Raddin[37] reported a single tree near Whiting. Nieuwland[38] reported this species from near Mineral Springs in Porter County, the report being based on his number 10,207 which I have not seen. There is no reason to doubt these references, because it is not an unusual thing to find a southern form jump from southern Indiana to a congenial habitat about Lake Michigan. =Remarks.=--Wood is similar but tougher than white oak, and its uses are the same as white oak. Since in our area the tree is usually medium sized, most of the trees are worked up into crossties. A tree in a black oak woods 4 miles east of Washington in Daviess County measured 2.22 meters (87-1/2 inches) in circumference breast high. This species in some localities is called iron oak, and in Gibson County on the sand dune area it is called sand bur oak. [Illustration: Plate 46. QUERCUS MACROCARPA Michaux. Bur Oak. (× 1/2.) Acorns from different trees. The right two belong to the variety OLIVÆFORMIS.]