Photographed in Rockcliffe Park. This is a tree native to southern Ontario and the US. In Ottawa it is considered quite invasive as it spreads rapidly. At the Fletcher Wildlife Garden, the trees have grown quickly and in some places, especially on the land adjacent to the garden, have seeded so prolifically that they are creating a mini woodlot of locust trees. Their flowers are creamy white and pendulous, and their seed pods elongate and pea-like (this is a member of the pea family - Fabaceae). Their thorns, as shown here, are very sharp!