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Wisconsin Plant of the Week

Parnassia glauca Raf.

Saxifragaceae (Saxifrage Family)

Common Name:

grass-of-parnassus

09/29/2002

Grass-of-parnassus, which hardly looks like a grass, is a native forb of fens, moist prairies and interdunal flats along Lake Michigan.  It grows in limy sands or peat soils where the water table is near the the surface, and where the water level is fairly stable through the year. The plants are up to 30 cm tall and if undisturbed will self seed to form clumps and large patches.

Grass-of-parnassus has beautiful flowers 2 to 3 cm across that sit singly on top of thin stiff stems.   Leaves are oval with a long stalk, shiny green and leathery, and clustered at the base of the plant. While the white petals are more typical of our spring flora these flowers bloom late in the summer from August to mid-October.

Each flower has five separate petals with grey-green veins and two kinds of stamens.  The five located between the petals are functional with pollen bearing anthers.  Alternating with these fertile stamens are 5 more stamens without pollen (staminodes).  Each staminode is divided into 3 lobes, each lobe with a yellow gland on the tip.  The fruit is a 4-parted capsule that splits open when dry to release many tiny seeds.

Wisconsin has two similar species that are much less common.   P. palustris (State Threatened) has a prominent stem leaf and 9 lobes per staminode. P. parviflora (State Endangered) also has a prominent stem leaf and all leaves are much narrower than in the other two species.

The Saxifrage Family isnít well-defined. The few species that occur in Wisconsin have mostly basal simple leaves, radially symmetric flowers with 5 separate petals and 5 or 10 stamens, all attached to the edge of a cup-like base, with a 2 or 4 parted ovary in the center.

  • Origin of the name: Parnassia, from Parnassus in Greece, where the genus is native; glauca, L. glauciam, pale grey-green
  • Range: Eastern N. Amer. s. to e. SD, PA, limited to glaciated areas with limy soils
  • WI Range:  Eastern and southern portions of the State where soils are calcareous. 
  • Common associates: Kalmís lobelia, small fringed gentian
  • Wetland Indicator Status: OBL
  • Coefficient of Conservatism: 8, WI; 8, MI; 10, Chicago Region
  • Related Sites: WI State Herbarium
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