The genus Parnassia, also known as grass of Parnassus or bog-stars, are flowering plants now placed in the family Celastraceae, formerly classified in Parnassiaceae or Saxifragaceae. The plants occur in arctic and alpine habitats, as well as in dune systems and fens, swamps, wet meadows, open seepage areas, moist woods, and across the Northern Hemisphere. It is actually not a grass, but an herbaceous dicot. The stalk of the plant can reach up to 200 millimeters (8 in), the leaves up to 100 mm (4 in) and the petals can be up to 36 mm (1.4 in) wide. The flower has five white petals with light green venation. There are five stamens alternating with 5 much divided staminodes tipped with drop-like false nectaries which (along with the visual cue of veins) attract pollinating flies and bees.

Some species are often found in wet calcareous habitats with low fertility, low canopy cover, and high plant diversity. Parnassia glauca is considered to be an indicator species of fens in New York State. Such habitats are often becoming rare, and so species of Parnassia may have high conservation value. For example Parnassia palustris is threatened and legally protected in Michigan while Parnassia caroliniana is considered imperiled in North Carolina.

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