Awww.... I'm imagining the poor neglected thing. :-)

It could be that the "stowaway" has sunk too deep over the years to do much of anything. You might be able to lift the rhizome(s) up to no more than 2" below the soil level and see what happens with it next year. Otherwise, you could attempt to dig it up (it will probably have a massive root system) and move it. You can do that in the fall.

You may be onto something.

The beds have way too much arborvitea mulch turned topsoil in them. I cleared away arborvitea mulch, fully 4 inches deep, from the inside of the azaelas in the opposite bed. In the stow-a-way's bed the topsoil literally washes over the narrow cement walk in front of it and into the grassy area on the other side of the walk when it rains.

How should I lift the rhizome(s) up to no more than 2" below the soil level? Should I accomplish this by taking a soft paint brush, and brush away the soil in between the stems of the plant? (We have lots of very good, very soft paint brushes at our house.)

Since it has sprouted, you could scrape away the soil that has covered the rhizome (don't necessarily need a paintbrush but could use a spoon or small trowel). Then in the fall, consider actually getting a pitchfork or shovel, go down deep along the side of where the sprouts were, and then attempt to heave it up so it is sitting a bit higher than it is now. Some roots will break but it would have time to grow some new ones before the dead of winter. You won't need any mulch around it.

Will do. Thank you very much!