Likely a seedling rather than a runner.

It can't be a seedling from the zebra grass because the original plant has never bloomed. I've only had it in the ground since July of the previous year. I'm hoping to see some blossoms for the first time this fall. None of my neighbors have Zebra grass.

I doubt your stray grass is a zebra grass. They don't send out runners, especially 3ft. away. As far as I know all miscanthus sinesis stay strictly in clumps.

Jean and Dereks,

Having watched my mystery grass grow for awhile longer, I can see that you are both correct about it not being zebra grass. It is over 3 ft. tall now, and unlike zebra grass, the lower stems and the edges of the blades are red. It has already begun to bloom, while the zebra grass is showing no sign of blooming yet. Also some of its stalks are horizontal rather than upright. I am sure you are correct, Jean, in saying that it must be a seedling (from some other kind of grass). I am happy to hear that Miscanthus sinensis species stay strictly in clumps.

Thank you both for your advice.

Anne