This one, being a branch
Hmmm. I recall reading somewhere about conifirs (living trees), having branches that liked to droop when dry and spread upward when it rained (to collect more moisture presumably). I even started a thread a few years back asking about this, and no one offered any observations in reply as I recall.
If so, perhaps branch wood tends to move more with humidity changes. I do know that there is reactionwood in branches because they grow horizontal, and if one does not take care with stave collection such that a bow ends up not having the reactionwood aligned properly, then the bow will tend to warp sideways if it was taken from the side of the treebranch