As I weed out couch grass rhizomes from my wood chip mulched garden, I'm observing that mycelium seems to be more frequently intermingled with its roots than other plants I pull out. Could it be that couch grass is symbiotic with fungi?
Also, an area that had 10cm wood chips put down two summers ago is now dominated by that stuff. I think that's because the rizomes are best at recolonising wood chip mulch. What are your observations?