A pin oak on Washington Square Park N., whose hollow trunk had been filled with concrete, and which the Parks Department sawed down on Thursday, drew the attention of curious passersby. Local rumor had it that the hollow was sealed up to keep dealers from stashing their drugs there. But according to Carli Smith, a Parks spokesperson, the concrete was added to stabilize the empty trunk, which subsequently did sprout a new limb. But when it was discovered the limb was also hollow, and given the tree’s location, it was decided it was a safety hazard and had to come down. Smith said Parks has a new pin oak earmarked to plant in the spot.