Here we can see an example of a Willow branch that was included in the main trunk.

As shown by the black and white chatoyance maps reported after the animated gifs, chatoyance is substantially similar within the main trunk and within the branch:

Similar conclusions may be drawn from these Mimosa (Acacia Dealbata) samples, kindly provided by mr. Dario Valentini.

Here we can see the area around a White Mulberry crotch:

And this is around a branch on a different Mimosa (A. Dealbata) tree:

And this is around a branch on a Tasmanian Blackwood (A. Melanoxylon) tree: