The mimicry of fire was fitting, because prairie grasses are adapted to thrive where periodic fires sweep through. Each fall, when they die back to the ground, they leave above them persistent remains ready to feed a fire. If no fire comes, that persistent dead foliage can get in the way the next spring, casting inhibiting shade on the new growth.
No fire will sweep through this ornamental planting. Hopefully, someone will imitate fire to some extent by cutting the old stems to the ground next spring so the new stems can grow unhindered.
The fiery version in front of town hall was surely a cultivated variety bred for especially dramatic color. But the prairie grasses in Ann Arbor that appeared to be aflame were wild. For some reason, perhaps a milder climate, the same species growing wild at Tusculum or along the gas pipeline right of way in Princeton don't attain that dramatic fall look.
When I lived in Durham, NC, I often found additional species of native prairie grass persisting beneath powerlines, where they were spared the stifling shade of trees. One that was particularly beautiful when backlit was splitbeard bluestem. Its cottony-like seeds seemed to glow when they caught the autumn sunlight.
It's good to see native prairie grasses showing up in plantings around town. The university seems to be learning how to maintain them better, which means catching the weeds early. Nice to be surprised by some sideoats grama poking through the fence at the soccer field.