Jenny Mackness's blog has more to say on rhizomes (and centres) ...

One way to think about whether learning is centred or decentered, perhaps, is to combine (and mix) metaphors a bit, and think about learning (and language) as de-centred-with-nodes.

So, decentered ...
... because the meaning of a sign comes from its use (Barthes' "every use becomes a sign of itself" - from hand-axes to mathematical notations) within a community of users - and the community is dynamic, it's an emerging ecology which has no permanent centre, if a centre at all. (No 'ultimate signifier', in the language of deconstruction, all we have is difference / différance).
Similarly with the use of material artefacts, where repeated use similarly creates 'residues' - innovative materials and social forms (hand-axes, mobile phones, tribes, families) that 'settle down' to become part of the physical and social furniture.

And 'nodes'...
... i) some ideas become knowledge: e.g. Seymour Papert's 'powerful ideas' or Meyer and Land's 'threshold concepts'. ii) some practices become established, routinised, some into 'memes' (social practices), some of which get further rendered into 'temes' (technical practices - see Susan Blackmore's "genes, memes and temes" on Youtube).

And some of the knowledge and practice becomes more formalised, and even more abstract and decentered in the concepts, algorithms and technologies of science, which builds capital - intellectual capital, manufacturing capital, networking capital, etc, which can be used by anyone, anywhere, anytime.

But, you might say, this still looks beguilingly like a 'centred' approach - building up intellectual capital through a series of cumulative nodes (Newton's famous saying that he was not that innovative, he was merely 'standing on the shoulders of giants'). But this too is dynamic: Newtonian physics gets displaced by relativity, gets displaced by quantum mechanics, all of which might one day get displaced by a Unified Field Theory, etc, etc.

So, finally ... 'decentered-with-unstable-nodes' ...
...is about as far as I can go (wearing my semotics / deconstructivist / post-modernist hats). I am not sure a rhizome on its own captures enough of this for me - Bateson's ecology of Mind works better at an abstract level, and Kevin Beiler's images of the Douglas Fir/ Micorrhizal Fungi ecology works better, for me, at a material level.