Clara Henriette Hasse (1880 – 10 October 1926) was an American botanist whose research focused on plant pathology.

[2] After graduating from the University of Michigan in 1903 with a PhB,[3][4] she went to Washington, D.C., to take up an appointment as assistant horticulturist and botanist in the Bureau of Plant Industry at the U.S. Department of Agriculture under Erwin Frink Smith, the USDA's pathologist-in-charge.

[3] Hasse was one of the twenty assistants that Smith hired during his tenure at the USDA.

Her work was included in Department of Agriculture bulletins to index the diseases of economic plants.

[10] Thomas Swann Harding credits this research with resulting "in control methods which prevented this disease from wiping out the citrus crop in Florida, Alabama, Mississippi, and Texas.