marsh grass of Parnassus

LC - Least Concern

NNR - Unranked

SNR - Unranked

not listed

OBL - Obligate wetland

OBL - Obligate wetland

OBL - Obligate wetland

Marsh grass of Parnassus is a 8″ to 16″ tall, erect, perennial forb that rises from a short, thickened, underground stem (caudex) and fibrous roots.

Basal leaves are on long leaf stalks and form a rosette. The leaf stalks are 1½ to 4 times as long as the blades. The blades are stiff, leathery, hairless, broadly egg-shaped to almost circular, 1⅛″ to 2″ long, and ⅝″ to 1¾″ wide. They are ¾ to fully as wide as they are long. The base is usually heart-shaped, sometimes broadly rounded. The blade does not extend down the leaf stalk below the point of attachment. The margins are untoothed.

A single, unbranched, hairless, 8″ to 16″ long flowering stalk (scape) rises from the rosette of basal leaves. There is usually a single leaf-like bract at or well below the middle of the stem. The bract is stalkless but otherwise similar to and the same size as basal leaves. The blade is broadly egg-shaped. It is heart-shaped at the base, and clasps the stem at the base.

The inflorescence is a single flower held erect at the end of the stem.

The flowers are ¾″ to 1½″ wide. Each flower has 5 green sepals and 5 white petals. The sepals are ⅛″ to 7 ⁄16″ long and elliptic. The petals are narrowly to broadly egg-shaped, ⅜″ to ½″ long, 1½ to 2 times as long as the sepals. Each petal has 5 to 17 greenish-yellow veins. The 5 center veins are usually unbranched. There are 5 white stamens with brown anthers. There are also 5 white sterile stamens (staminodes) that are divided into 9 to 23 slender filaments for 3 ⁄5 or 4 ⁄5 of their length. Each filament is green or yellow, 3 ⁄16″ to ⅜″ long, and topped with a modified anther reduced to a gland. The staminodes are a little shorter than the stamens.

The fruit is a 4-valved, egg-shaped, 5 ⁄16″ to ½″ long capsule with numerous seeds.

8″ to 16″

White with dark green veins

Fen grass of Parnassus (Parnassia glauca) has a smaller bract, smaller than the basal leaves. The bract does not clasp the stem. The staminodes are white, and are divided near the tip into 3 filaments.

Wet; meadows, shores rich in lime.

July to August

Sources

2, 3, 4, 5, 7, 28, 29, 30.

Native

Fairly common

GBIF recognizes seven varieties. Four of these occur in North America and one occurs in Minnesota.

USDA PLANTS recognizes four varieties in North America. Two of these occur in Minnesota.

GRIN and ITIS recognize no varieties.

Plants of the World Online recognizes three varieties. Only the nominate variety, Parnassia palustris var. palustris occurs in North America.

World Flora Online recognizes one subspecies and two varieties, none of which occur in North America. Presumably, only the unlisted nominate species occurs in North America.

Flora of North America (FNA) mentions the profusion of varieties that have been described in Eurasia and North America, but does not formally recognize them.