Hartmaniella oxyphylla, the robust starwort or Robinson's starwort, is a rare species of plant endemic to the north-western United States, where it is known only from Kootenai and Shoshone Counties, Idaho. It grows along stream-banks in conifer forests at elevations of 800âÂÂ900 m.
Hartmaniella oxyphylla is an annual herb with fibrous roots. Stems are 4-angled, up to 30 cm long, with a thin line of hairs along one side. Leaves are narrow, up to 12 cm long. Flowers have green sepals and white petals.