[FRIAM] looking for a word

[uǝlƃ ☣]

I need a word (or short phrase) to refer to the portion of a network where the edges converge or diverge (more than other parts of the network.  Examples might be a river delta or the branching (debranching?) of blood vessels or lungs.  "Plexus" or "knot" don't work because they could ambiguously refer to something like a tapestry or ... well, a knot, where each thread remains separate, but winds around other threads.  Something close to "canalization" seems appropriate. But I don't want to imply the generation (or dissolution) of the thing.  E.g. [arter|ang]iogenesis are not the type of words I'm looking for.

There's got to be a good word for such, perhaps from graph theory or "network theory".  Any help will be rewarded by an IOU for a pint of beer. 8^)

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☣ uǝlƃ