rhizomes are plants that tend to grow horizontally rather than vertically. Rather than sending their roots dep into the ground, and rather than being clearly unified and distinct entities, rhizomes spread out, climbing up and all over things that are in their way, getting tangled up with other rhizomes. Think of grass, or of ivy climbing up and over what ever it comes acrss. If philosophers approach things as rhizomes (instead of trees), they will come up with a very different picture of how things are.