Abandoned railway embankment
Gravel pit. Sparsely vegetated. Nectaring on Cerisium arvens.
Mixed-grass prairie habitat. Far SW Manitoba, general location. I don't remember precise location.
Traditionally used to treat heart ailments, diarrhea, broken bones, and as an astringent (to close bleeding wounds).
Ref: http://www.museum.state.il.us/muslink/forest/htmls/trees/Q-macrocarpa.html