it looks a little wavy from the half I can make out, the far end is out of focus. I am going to guess you went to the the big orange box supermarket "lumberyard"? or something like it? there is a good chance their oak is substandard in ways that are not obvious also.
We don't have big box stores here; I got this from Bloedorn Lumber, a semi-local chain. Not sure if that matters.
looking at the center of a flatsawn board where the rings are truly flat can be deceptive in that a series of islands can be evident as a single ring wanders in and out of the face cut. worse is a series of flame points pointing in the same direction, then maybe reversing until another island is found. this indicates a number of rings being violated.
I thought that violated rings weren't a problem with a board bow. That in itself has always confused me: Why is that such a no-no on a stave, but boards don't need to follow a ring? For that matter, hickory backing doesn't need to follow a ring. Why?
what kind of saplings grow along the river bottom?
Mostly cottonwood and aspen. Chokecherry is pretty common in the foothills, as is rocky mountain juniper. Both are going to be full of knots, so would probably need to be sinew backed. I know of a few rowan/mountain ash, but they're quite rare, and odds of finding a good stave are pretty low. That's about it for native bow woods. I would love to do a chokecherry/sinew bow, but I was hoping for something a bit easier and more immediate to get me started.
Thanks for trying to answer my myriad questions, guys. I'm trying to figure out the why, not just the what. It's so much simpler when the guys in youtube videos do this! ha ha