There was major flooding around here and water took a lot of soil. River bank changed considerably and it washed whole trees including the roots down the river. There are two Phyllostachys groves on the same river bank. Not the largest groves, but quite dense with culms up to two inches thick. Both grooves were practically intact when water level dropped. Few rhizomes could be seen on top of river bank, but not nearly as much as with several trees nearby that ended up without any soil around the