Isotoma is a genus of annual and perennial herbs in the family Campanulaceae and are native to Australia and New Zealand.

Plants in the genus Isotoma have milky sap, a distinct taproot and sometimes adventitious roots along the branches.

The petal tube is slightly zygomorphic with five lobes spreading horizontally, the upper two smaller and the lower three often with distinct markings.

[2][3] In 1810, in his book Prodromus Florae Novae Hollandiae et Insulae Van Diemen, Robert Brown described Lobelia hypocrateriformis and placed it in section Isotoma.

[4][5] Then in 1826, based on Brown's description, John Lindley raised the genus Isotoma in The Botanical Register.