The Rhizome

Gilles Deleuze and Félix Guattari used the term "rhizome" to describe theory and research that allows for multiple, non-hierarchical entry and exit points in data representation and interpretation. In A Thousand Plateaus, they opposed it to an arborescent conception of knowledge, which worked with dualist categories and binary choices. A rhizome works with horizontal and trans-species connections, while an arborescent model works with vertical and linear connections. Their use of the "orchid and the wasp" was taken from the biological concept of mutualism, in which two different species interact together to form a multiplicity (i.e. a unity that is multiple in itself). Horizontal gene transfer would also be a good illustration.
Rhizome theory is also gaining currency in the educational field, as a means of framing knowledge creation and validation in the online era. Glynis Cousin applies the concept when critiquing existing VLEs (virtual learning environments) in her 2005 paper "Learning from Cyberspace". Dave Cormier (2008) criticizes the limitations of the expert-centered pedagogical planning and publishing cycle and posits instead a rhizomatic model of learning. In this rhizomatic model, knowledge is negotiated, and the learning experience is a social as well as a personal knowledge creation process with mutable goals and constantly negotiated premises. The rhizome metaphor, which represents a critical leap in coping with the loss of a canon against which to compare, judge, and value knowledge, may be particularly apt as a model for disciplines on the bleeding edge where the canon is fluid and knowledge is a moving target.

"Let us summarize the principal characteristics of a rhizome: unlike trees or their roots, the rhizome connects any point to any other point, and its traits are not necessarily linked to traits of the same nature; it brings into play very different regimes of signs, and even nonsign states. The rhizome is reducible to neither the One or the multiple. It is not the One that becomes Two or even directly three, four, five etc. It is not a multiple derived from the one, or to which one is added (n+1). It is comprised not of units but of dimensions, or rather directions in motion. It has neither beginning nor end, but always a middle (milieu) from which it grows and which it overspills. It constitutes linear multiplicities with n dimensions having neither subject nor object, which can be laid out on a plane of coinsistency, and from which the one is always subtracted (n-1). When a multiplicity of this kind changes dimension, it necessairly changes in nature as well, undergoes a metamorphisis. Unlike a structure, which is defined by a set of points and positions, the rhizome is made only of lines; lines of segmentarity and stratification as its dimensions, and the line of flight or deterritorialization as the maximum dimension after which the multiplicity undergoes metamorphosis, changes in nature. These lines, or ligaments, should noty be confused with lineages of the aborescent type, which are merely localizable linkages between points and positions...Unlike the graphic arts, drawing or photography, unlike tracings, the rhizome pertains to a map that must be produced, constructed, a map that is always detatchable, connectable, reversable, modifiable,, and has multiple entranceways and exits and its own lines of flight." (see Deleuze & Guattari, 1987, p. 21)