Northwestern Bur Oak

Tree Description:

94-05     A northwestern bur oak (Quercus macrocarpa forma oliviformis) similar to 95-21, this tree is adapted to the northern Great Plains, having tiny acorns that mature in a short growing season and being very tardy in breaking winter dormancy as an adaptation to long northern winters. We are in the heart of the natural range of bur oak here with great genetic variation. Perhaps surprisingly, this one which is so typical of central Canada was grown from a group of spontaneous old Oak Ridge trees southwest from Lincoln’s tomb. Others can be found nearby that look like those from Texas. However, neither Canada nor Texas shows this amount of diversity, as the types sort out according to their adaptive capabilities.

Location:     39.825431 N, 89.663408 W

Map:     Get walking directions here.

Tree Description:

95-21     Another northwestern bur oak (Quercus macrocarpa forma oliviformis) similar to 94-05, this specimen was grown from tiny acorns produced by a tree planted long ago along the south side of the Illinois State Museum. The original tree is very slow growing with tiny, early ripening acorns, which would be expected in a place such as Saskatchewan. There were no other pollen-compatible oaks in the vicinity of that tree so we believe it was self-pollinated. Compare it with tree 94-05 and then with other bur oaks in our area. You might notice that this species is one of the most variable oaks found in North America.  Each of these trees can be considered within the described limits of the somewhat artificial category oliviformis, yet each is different. We say “artificial” because bur oaks vary clinically (gradually from place to place) and there are no distinct varieties officially recognized today.

Location:     39.825431 N, 89.663408 W

Map:     Get walking directions here.

 

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