"Moon phase rings" ? in osage. anybody know?

[PatM]

I see more mini-rings in the stave Dean posted. Where is he from?
 I doubt it takes more than a month for the early wood, because it is also a lunar ring. 

[SLIMBOB]

My question is, is that what really happens. Is there always a clearly identifiable point at which early wood production ends and late wood production begins?  I have seen many staves where it appears as though the trees early attempts at producing latewood were not as successful as the attempts later in the growing season.
I do want add that this is how I have interpreted what I have seen. I am willing to be wrong if in fact there is evidence to the contrary.

[PatM]

Literature on that subject indicates that early wood formation is initiated as the tree buds begin to open and latewood begins forming when the leaves are fully developed.