This is widespread across central North America, with some eastern extensions. In Ky. and Tenn. it is strongly concentrated in the Bluegrass region, the Nashville Basin, and some rich bottomlands along larger rivers to the west. In the central Bluegrass, Short (1828-9) noted: "This noble species is every where met with in the rich forests of this neighbourhood, towering above the most of other trees and throwing out its large umbrageous branches to a considerable distance around." In Ky., there appear to be occasional hybrids with alba, bicolor, muehlenbergii and perhaps other species. Also, there was probably some early confusion with lyrata in Ky. before 1860, when both species were sometimes called "overcup oak" (Campbell 1989). Most of the unverified historical data of Gm and B are mapped here as open dots. Reports of Gm and Little (1971) from the Appalachian Plateaus of Ky. remain dubious. But the species does occur rarely in Appalachian valleys of se. Ohio, and perhaps sw. W.Va. according to some sources (K but not Little or HFG). Q. macrocarpa was probably associated with concentrations of larger animals, and its seedlings (as in stellata) appear to be much more tolerant of mammalian predation than muehlenbergii or alba. Its unusually large acorns are somewhat protected by "burs" and drop relatively late, mostly in mid-Oct. They are often cached by squirrels to locations where they do not germinate until spring, unlike the fall-germination of most white oaks. Q. macrocarpa may require 1-2 months of stratification, as in the red oaks (USFS 1948; Schroeder & Walker 1987). Its twigs are relatively thick (mostly 3-4 mm), usually pubescent when fresh (but not tomentose as in stellata), and after 1-2 years often forming distinctive, flat-topped, corky wings (especially on saplings and young trees); see FNA 3. Across its range, macrocarpa varies significantly, due in part to gene exchange with other species, especially in chloroplast DNA (Whittemore & Schaal 1991). Plants from the Ohio Valley, central and lower Mississippi Valleys tend to be distinct from those in more northern and western sections of the range, with larger acorns, longer peduncles, larger leaves, shade or juvenile leaves with less pubescence and shallower lobing (sometimes resembling muehlenbergii), more corky twigs (after 3-4 years of growth) and stems (with less flaky bark), faster tree growth (up to 25 mm in diameter per year), and larger overall maximum tree size (up to 240 cm dbh). Unusual forms have been developed into cultivars, such as "Big John" (at Forrest Keeling Nursery in Mo.), which has relatively dense upright ("fastigiate") branching and produces no few or no fruit, thus sometimes recommended for urban use (Jablonski 2012).