Whatever it is, it's beautiful.

Looks like horse-chestnut/buckeye to me.

I too think it is Aesculus possibly pavia but a close up of the leaves and flowers would help. pavia usually doesn't get as big as the picture seems to show, at least around here but again, a close up would help.

It's the Red Buckeye...Aesculus pavia. This wonderful plant grows well within your Southern Illinois home. It's a fine native plant and a favorite of hummingbirds. The 'nuts ' are toxic.

Thank you, everyone...

No close up Gandle... have to wait until next May and June when it 'blooms' again. One tree in the local town is at least 45 tall, can be seen from some distance away... others are small due to not being very old.

I know that water, climate and acidity in soils can affect
the hue of blooms the world over... suspect this tree is no different, some 'blooms' are so bright red the red and green contrast look like christmas; others are orange to
tan..

Pretty to look at.

s

I grow and propagate red buckeye and even have an allee made of them. They can be tough to differentiate from the red chestnut, but when your conkers or buckeyes form, it's easy to tell the difference. Red buckeyes have a smooth hull and chestnut have a spiny or nubby hull. Hybrids between them as the Briotti have the spiny hull as well.