The Seed That Splits the Concrete

In downtown Detroit, along a stretch of abandoned sidewalk near Michigan Avenue, a single maple seed once lodged itself in a hairline crack in the concrete. No one planted it. No one watered it. The seed carried no impressive résumé — it was small, papery, the kind of thing you brush off your windshield without a second thought. But inside that unremarkable shell lived a force that engineers still marvel at.…