harebell

noun2

1. •
   A perennial flowering plant, Campanula rotundifolia, native to the Northern Hemisphere, with blue, bell-like flowers.

   • How Snow-drops cold, and blue-eyed Harebells blend / Their tender tears, as o'er the stream they bend […]. — 1789
2. •
   foxglove

   • I wonder whether the witches would be wearing on their fingers their ornaments of foxglove blossoms, often called witches' bells or harebells, sometimes known as witches' thimbles. — 1940