The Black Locust of Krayenhoffpark

The Dutch name for this tree translates literally as false Christ's-thorn, a reference to the sharp paired spines that line its young branches, thorns sharp enough that European folklore once linked the species to the biblical crown of thorns despite the tree being a North American import that no one in the region had ever seen before the 17th century. This specimen, dated by the register to around 1880 to 1890, predates its own park: Krayenhoffpark and the railway workers' housing around it were built in the early 20th century, decades after this tree first went into what was then open ground on the edge of the city. Black locust fixes nitrogen in the soil through bacteria living on its roots, the same trick clover and beans use, which is part of why it was planted so widely across poor European soils long before anyone understood the chemistry behind why it thrived where other trees struggled. It stands a few steps from the park's hornbeam and its better-known giant sequoia, free, the oldest of the three despite being the least conspicuous.