Please / Thanks:

Seattle/Pacific Northwest - Have been remaking a client's yard (jungle wasteland....) and have come across a swath of a perennial (presume it's that as she has done NADA with her yard for literally years and this plant has persisted); appears to grow at least 3'-5'+ tall from the looks of the limp leftovers; is a rhizome which has sent its messengers along quite some distances just under the surface; best I can describe them is that they have somewhat a "carroty-like" look to them; when broken/sliced, rather orangeish, similar to the interior of some types of squash.

Any seers out there...? Thanks!