This section is from the book "Handbook Of Hardy Trees, Shrubs, And Herbaceous Plants", by W. Botting Hemsley. Also available from Amazon: Handbook of hardy trees, shrubs, and herbaceous plants.
Stemless herbs with radical entire leaves and 1-flowered scapes. Flowers white or pale yellow, about an inch in diameter, pentamerous, 5 fertile and 5 sterile stamens alternating. Capsule 1-celled, loculicidally 3- or 4-valved, many seeded. About twelve species, from the northern temperate and frigid zones.
1. P. palustris. Grass of Parnassus. - An indigenous species. Leaves cordate-ovate, acute, one to two inches long, on slender petioles. Scape about a foot high, with one sessile leaf about the middle.
P. asarifolia with reniform leaves, and P. Caroliniana with cordate-ovate obtuse leaves, are North American species. All are very pretty and interesting.