There are 3 types of board cuts. As viewed from the end or butt plain sawn looks like this ==, quarter sawn looks like this || and rift sawn looks like this //.
Those points are in someone's pic above /\ are fro plane sawn are ok. I think it just means the trees top is decreasing in diameter.
I like rift sawn and don't favor quarter sawn.
Look for straight grained stock as the ideal. Tip to tip. I look at the edge grain but for plane and rift the edge grain will reflect the face too.
Plane sawn and quarter sawn will allow a couple of runouts per limb where the grain goes belly to back at a gradual angle.
Quarter sawn will tolerate no runouts. Look at the edge grain. It must be straight tip to tip.
I know what it is like to want to build a bow believe me. But if you don't find a good board then leave. Don't compromise. Don't compromise.
Also TBB #2 has info. TBB #4 also. I got started with TBB 2 when it first came out. I like read oak because it is s plentiful.
Check my site too. Lots of board info.
One ore thing. No knots allowed no matter how small.
http://traditionalarchery101.comJawge