Columbine, or Aquilegia, is in bloom right now. The white one below (most likely a cultivar of A. hybrida) is growing just near the courts at Tompkins Square Park.
Many columbines are native to the Rockies and other mountainous areas in the west. They grow best at high altitudes, but are very popular perennials elsewhere. They self-seed readily but are not invasive. A spring ephemeral, the foliage will die back in late June, when the weather gets quite hot.
I suspect part of the reason the plant is so popular in the nursery trade is due to the very showy, very unique flower structure. The petals form into nectar spurs. That alone may be hint enough that one of the pollinators of this plant is a moth -- moths have long proboscises to access the nectar. Native Americans would often use the flowers as an edible garnish, but other parts of the plant are highly toxic.
Aquilegia -- of which there are over sixty species -- is in the Ranunculaceae, or buttercup, famliy, and is a relative of the also-toxic Aconitum.