Parnassia glauca (American Grass of Parnassus)

Plant Info
Also known as: Fen Grass of Parnassus, Grass of Parnassus
Genus:Parnassia
Family:Parnassiaceae (Grass-of-Parnassus)
Life cycle:perennial
Origin:native
Habitat:sun; calcareous fens, wet meadows
Bloom season:August - September
Plant height:8 to 16 inches
Wetland Indicator Status:GP: OBL MW: OBL NCNE: OBL
MN county distribution (click map to enlarge):Minnesota county distribution map
National distribution (click map to enlarge):National distribution map

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Detailed Information

Flower: Flower shape: 5-petals

[photo of flower] Flowers are white, ¾ to 1 inch across, single at the end of a long, slender, stem. The 5 petals are egg shaped with conspicuously  "embossed" veins that extend all the way to the edges, a few veins may be minimally branched. The egg-shaped ovary of the central pistil is greenish white with a 4-parted stigma at the tip and is surrounded by 5 stamens that are more than half as long as the petals, and spread out between the petals. The stamen tips are initially creamy colored but quickly turn yellowish brown then fall off. Between the fertile stamens, at the base of a petal, is a set of 3 white sterile stamens, 1/3 to ½ the length of the 5 fertile ones, tipped with yellowish glands.

sepals and stem The 5 spreading sepals below are green, typically with purple tips, narrowly egg-shaped and less than ¼ the length of the petals, completely hidden from above by the overlapping petals.

Leaves and stems: Leaf attachment: alternate Leaf attachment: basal Leaf type: simple

[photo of leaves] Leaves are leathery, mostly basal, the blades mostly egg-shaped, 1¼ to 2 inches long and 2/3 to 1¾ inches wide, toothless, hairless, rounded or with a soft point at the tip, rounded or nearly heart-shaped at the base, on a stalk 1 to 2 times as long as the blade. A single stem leaf, when present, is well below the middle or nearly at the base of the stem, stalkless, the blade smaller than the basal leaves but a similar shape or somewhat more triangular. The flowering stem is hairless and angled.

Notes:

Perhaps the common name describing it as a "grass" is a misnomer, but without the bright single flower at the very tip of its long, slender stem, it would be very hard to discern from the grasses that surround it, the basal leaf cluster often buried in the vegetation. There are two Grass-of-Parnassus species in Minnesota and while they are not necessarily uncommon, both inhabit fen or ground water seepage habitats that are not frequented by people but have suffered serious decline in recent years from development, agriculture and invasive species. Of the two, P. glauca occurs mostly in calcareous fens more common in southern and western regions of the state while Marsh Grass of Parnassus (P. palustris) prefers rich or spring fens more common in north central and northeastern counties. While very similar in growth habit and flower, they are easily distinguished by several obvious differences. In comparison, the leaves of P. palustris are more broadly heart-shaped with rounded basal lobes, tapered towards the tip, especially the stem leaf, which has its basal lobes clasping the stem. In its flowers, the sepals are rather longer than P. glauca, visible between the petals. The reduced, gland-tipped sterile stamens are clustered in far greater numbers with 5 or more, 12 to 14 on average. Of note is that other references state the stem leaf of P. glauca is not clasping, but from our own photos and personal observations it may seem nearly so.

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More photos

Photos by K. Chayka taken at Seminary Fen SNA, Carver County, and Blue Stem Prairie SNA, Clay County. Photos courtesy Peter M. Dziuk taken in Carver and Clay counties.

Comments

Have you seen this plant in Minnesota, or have any other comments about it?

Posted by: Deane - Twin Lakes SNA, 10 mi. NW of Karlstad
on: 2015-08-27 16:58:01

There were a few groups of these growing in the beautiful wet prairie on the minimum maintenance road about 1/2 mile north of the cemetery in the main SNA unit.

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