Quercus macrocarpa Michx.  

Bur oak on uplands is often associated with calcareous soils. In  the "driftless" area of southwestern Wisconsin, it is  commonly found on limestone ridges; in Kentucky, it is more  prevalent on limestone soils than on soils derived from shales  and sandstone (5). In western Iowa, it can be found as a dominant  on soils of either limestone or sandstone origin. Throughout much  of the prairie region of the Midwest, bur oak is found on  droughty sandy plains, black prairie loams, and on loamy slopes   of south and west exposure. Toward the western edge of its range,  such as in eastern Kansas, it is more abundant on the more moist  north-facing slopes than on southfacing slopes (2). Bur oak often  dominates severe sites with thin soils, heavy claypan soils,  gravelly ridges, and coarse-textured loessial hills. The  predominant soil orders on which bur oak is found include  Alfisols in the central and southern parts of its range, and  Mollisols and Spodosols in the western and northern parts of its  range, respectively.

    Bur oak is also an important bottom-land species throughout much  of its range. In the Central States Region and southward, it is  found on moist flats and on hummocky bottoms. Northward, in  southern Michigan, it has been found in high densities on  slightly elevated ridges within wet bottom-land forests occupying  old glacial lake beds and drainage ways (20).

    Bur oak frequently forms a fringe between the prairie and upland  forest in northern Illinois and eastern Iowa, notably at the  outer edges of "breaks" and bluffs along streams and  around limestone outcrops. It is a valuable timber species on  favorable bottom-land sites within this region.

    Within the Great Plains Region, it is frequently found in stream  bottoms and stream terraces. In North Dakota, bur oak is a major  component of the flood-plain forests of the Missouri River (11).  Here it may predominate in old stands on high terraces near the  edge of the flood plain. It is absent in low terraces near the  center of the flood plain. Along adjacent draws and upper slopes,  it becomes the first tree established along prairie edges. Bluffs  along the Missouri River and its tributaries in eastern Nebraska  are frequently covered with bur oaks that range in size from  small trees near the base of bluffs to shrublike growth near the  top.

    In the Black Hills of western South Dakota and the Bear Lodge  Mountains of northeastern Wyoming, bur oak grows at low  elevations between the ponderosa pine forest and the grasslands  (21). Here, it ranges in size from a shrub under a pine canopy at  higher elevations to a tree up to 21 m (69 ft) tall along stream  bottoms at lower elevations.

Bur oak is monoecious; male and  female flowers in separate catkins are home on the current year's  branchlets. It flowers shortly after the leaves appear, from  about the first of April in the southern part of its range to  about mid-June in the north (5). Pollen from one tree appears to  germinate better on the stigmas of another, favoring cross  pollination.

Bur Oak is a common tree that is found in every county of Illinois. Habitats include moist bottomland woodlands, upland woodlands, and savannas where deciduous trees are dominant. This tree is most commonly found in bottomland woodlands a little outside of the flood zone. It also occurs in savannas and can be an invader of prairies because of its resistance to fire. Occasionally, Bur Oak is cultivated as a landscape tree, where it can become quite large.

More info for the term: tree

Bur oak acorns are animal dispersed. Small mammals are the most likely dispersers. Birds are less likely dispersers, given the large size of bur oak acorns. Likelihood of bird dispersal may increase if only bur oak acorns are available or if small acorns are produced in a given season or on a given site. One study reported that bur oak acorns were dispersed by blue jays in Iowa (Johnson unpublished data [124]), but in a later Iowa study, blue jays avoided bur oak acorns [127].

Animal-mediated dispersal distances as great as 490 feet (150 m) were reported in forest fragments in southern Ontario. Rodents were the suspected dispersal agent. In this study, researchers searched a maximum distance of 490 feet (150 m) between seedlings and the nearest fruiting tree, suggesting that acorn dispersal distances may have been even greater than reported [110]. Near Manhattan, Kansas, fox squirrels cached bur oak acorns an average of 59 feet (18 m) from the source pile [228], but when researchers evaluated the number of seedlings occurring beyond the woodland edge in the same area, bur oak seedlings were found a maximum of 169 feet (51.5 m) from the forest edge [229].