On osage we call it "chasing a ring" or following one growth ring, with no violation,from one end of the bow to the other on the back.
If you are using osage lumber you will need to back your bow with bamboo, hickory, rawhide, drywall tape or some other substance to prevent failure.
If you have a perfectly decrowned piece of lumber you may not have to back it but as you are a fledgling bowyer I would recommend backing. Bamboo would be my choice if I had a nice board to work with.