Campanula sharsmithiae is a rare species of bellflower known by the common names Mt. Hamilton bellflower and Sharsmith's harebell. It is endemic to California, where it is known from just a few occurrences in the higher mountain peaks just south of the San Francisco Bay Area, including Mt. Hamilton and Mount Boardman in the Diablo Range. It is a small, hairy annual herb producing an erect stem up to 25 centimeters tall. The fleshy, toothed leaves are a centimeter long or less. The flower is funnel- or bell-shaped and purple in color. The plant is named for late local botanist Helen Sharsmith.