Deschampsia flexuosa (Wavy Hairgrass)

Plant Info
Also known as: Crinkled Hairgrass, Slender Hairgrass
Genus:Deschampsia
Family:Poaceae (Grass)
Life cycle:perennial
Origin:native
Status:
  • State Threatened
Habitat:part shade, sun; dry sandy or rocky soil; pine stands, forest clearings, dunes, shores, rocky slopes
Fruiting season:July - September
Plant height:1 to 3 feet
Wetland Indicator Status:GP: UPL MW: FACU NCNE: FACU
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: indistinct Cluster type: panicle

[scan of panicle] Loose, open branching cluster at the top of the stem, to 6 inches tall and about as wide, erect or more often somewhat drooping. Spikelets (flower clusters) are single at the tips of slender branchlets, silvery to purple-tinged at flowering time, 4 to 7 mm (to ¼ inch) long with 2 florets.

[close-up of spikelet] At the base of a spikelet is a pair of bracts (glumes) that are both thin and papery, pointed at the tip, 1-veined, keeled, the upper glume 4 to 6 mm long and about as long as the spikelet or nearly so, the lower glume slightly shorter than the upper glume. Surrounding a floret are a pair of bracts (lemma and palea), the lemma 3.3 to 5 mm long, rough-textured, weakly veined, somewhat ragged or toothed at the tip, with an awn that arises from near the base of the lemma, extends 1 to 3 mm above the floret, and is bent at or just below the middle; the palea is slightly shorter than the lemma and 2-veined. The thickened base around the floret (callus) and the stalk between the florets (rachilla) are both covered in long, white hairs.

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

[photo of sheath, ligule and node] Leaves are mostly basal with 1 to 3 on the lower stem, stiff, erect to spreading, usually rolled in along the edges (involute), up to 8 inches long, 1 to 2 mm wide, hairless. Sheaths are smooth to slightly rough. The ligule (membrane where the leaf joins the sheath) is .5 to 3 mm long, rounded to pointed or notched along the tip edge and lacks a fringe of hairs. Nodes are smooth.

[photo of leaf clump] Stems are slender, hairless, multiple from the base, erect to ascending. Plants form dense clumps of mixed flowering and vegetative shoots.

Fruit: Fruit type: seed without plume

[photo of mature florets and grains] Spikelets turn pale tan as they dry, the pair of mature florets falling away together, leaving the glumes behind persisting on the stalk.

Notes:

Wavy Hairgrass, known as Avenella flexuosa in some references, is rare in Minnesota with only a handful of known locations, most of which are in the northeastern tip of Cook County. According to the DNR, it was listed as a Special Concern species in 1984 and elevated to Threatened in 2013 after biological surveys only discovered one additional population. In Minnesota it is found along the north shore of Lake Superior in rock crevices and in openings of pine stands, typically among the lichens.

It is distinguished by the dense tuft of stiff, hairless, mostly basal leaves that are commonly rolled in along the edges (involute); the open, airy panicle that may be somewhat nodding; spikelets up to 7 mm long, single at branchlet tips with 2 florets that are long hairy only around the callus and rachilla; lemmas that have an awn arising from near the base that extends 1 to 3 mm beyond the tip of the lemma and is bent at or below the middle. The other Deschampsia species in Minnesota, Tufted Hairgrass (D. cespitosa), is also found on the rocky north shore of Lake Superior, but is far more common; its lemmas have much shorter, usually straight awns that barely extend beyond the lemma tip, if at all.

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More photos

Photos by K. Chayka and Peter M. Dziuk taken on Minnesota Point in St. Louis County.

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