@sandi any update?

@teamcll this is similar to yours.

The difference with mine is, the trunk actually split wide open. I've seen air roots like these before, usually when it's is very wet and humid. I can't figure why it would just crack open on its own. Maybe growing too fast.

I stake all my plumeria that are in the ground, some 30 plants. Perhaps, Jason, plumeria "trunks" will crack when winds bend them back and forth. Plumeria are really top-heavy plants when fully leafed out. I'm simply guessing at the cause. In 30 yr. of growing 1000's of them, as far as I know, I've never seen air-roots on any of my plants. I do not believe growth rate is a factor.

Glad to have found this thread. My 25 year old plumeria seems to be sprouting roots (or something) from a branch. Hasn't been repotted in years.

You might want to do an experiment and cut that branch off right at the fork. See what happens when you root that cutting, @Purpleheather. The problem is that I don't see the full tree, so don't know what this branch looks like. I love to experiment and that's what I would do in this situation.