Parnassia palustris, commonly called marsh grass of Parnassus, northern grass-of-Parnassus, or just grass-of-Parnassus, and bog star, is a flowering plant in the staff-vine family Celastraceae. It is not a grass, nor does it look like one, but grows from a short underground stem. It has long stemmed heart-shaped leaves, which are 4-12 in (10–30 cm) long. In the centre of the leaf, is the flowering stem. The stem holds a solitary white flower, blooming between July and October. The flower has 5 stamens around the centre. The flower produces a honey-like scent to attract pollinators.
It is the county flower of Cumberland in England, and appears on its flag.