Actually the bamboo used to run over the limbs too, it was pulling a good 50+ lbs before it splintered though: too small a backing for such a wide bow I think. The overlays are pin cherry burl, they are very common on pin cherry trees here.
While I have dozens of staves, I often find myself coming back to the simple red oak board bow. The straight lines are really easy to tiller, the wood is easy to find and backings are very easy to apply. I probably make 3 oak board bows for every stave bow.