Rhizome is a figurative term used by Felix Guattari and Gilles Deleuze in their book A Thousand Plateaus: Capitalism ad Schizophrenia to describe non-hierarchical networks of all kinds.

"A rhizome as a subterranean stem is absolutely different from roots and radicles. Bulbs and tubers are rhizomes. Plants with roots or radicles may be rhizomorphic in other respects altogether. Burrows are too, in all their functions of shelter, supply, movement, evasion, and breakout. The rhizome itself assumes very diverse forms, from ramified surface extension in all directions to concretion into bulbs and tubers ... The rhizome includes the best and the worst: potato and couchgrass, or the weed." (Deleuze & Guattari, 1987, p. 6- 7)