Elymus curvatus (Awnless Wild Rye)

Plant Info
Also known as: Short-awned Wild Rye
Genus:Elymus
Family:Poaceae (Grass)
Life cycle:perennial
Origin:native
Habitat:part shade, shade, sun; average to moist soil; woods, floodplain forest, river banks, shores, wet meadows
Fruiting season:July - September
Plant height:2 to 4 feet
Wetland Indicator Status:GP: FAC MW: FAC NCNE: FAC
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: spike

[photo of spike] A single erect spike 3½ to 6+ inches long at the tip of the stem, with a pair of erect to slightly ascending spikelets (flower clusters) at each node. Each spikelet is 10 to 15 mm long (excluding awns) and usually has 3 or 4 florets, occasionally more or less; the uppermost floret may be sterile. Color is green to blue-green at flowering time, sometimes covered in a waxy bloom (glaucus). The base of the spike is sometimes enclosed in the uppermost leaf sheath.

[close-up of spikelets] At the base of a spikelet is a pair of bracts (glumes), both firm, hairless, minutely toothed along the edges near the tip, 3 to 5-veined, narrowly lance-linear tapering at the tip to a short, straight awn, 1.2 to 2.1 mm wide, 7 to 16 mm (to ~2/3 inch) long including the awn, usually longer than the florets, the base thickened, hardened for up to 4 mm, slightly to strongly bowed. Florets are surrounded by a pair of bracts (lemma and palea), the lemma usually hairless, 5 to 7-veined, the body 6 to 10 mm long with or without a straight awn less than 4 mm long; the palea is nearly as long as the lemma, hairless, 2-veined.

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

[photo of sheath, ligule and node] The 6 to 9 leaves are alternate, up to 12 inches long, up to 15 mm (~½ inch) wide, mostly flat, sometimes rolled along the edge (involute), usually hairless, smooth or rough-textured, fairly evenly distributed along the stem, and arching to floppy. The sheath is usually hairless and may or may not have a pair of small brown to purplish lobes (auricles) at the apex. The ligule (membrane where the leaf joins the sheath) is less than 1 mm long, more or less straight across, and lacks a fringe of hairs. Nodes are hairless and may be glaucus. Stems are unbranched, smooth, usually erect, single or a few from the base forming loose clumps, and may be glaucus.

Fruit: Fruit type: seed without plume

[photo of glumes (front and back), florets and grain] The awns remain straight as spikelets mature, all turning straw-colored to bleached tan when dry. Florets drop off individually as they mature, the glumes also dropping off often with the lowest floret, leaving the node stubs all along the stalk. Grains (seeds) are elliptic with a tuft of white hairs at the tip.

Notes:

There are 10 Elymus species in Minnesota (not counting vars/subspecies); Awnless Wild Rye is one of the less common in the state. It is most often found in moist, wooded habitats near rivers, less often on lake shores, roadsides, meadows or drier sites. We first encountered it in the wooded floodplain of the Red Eye River in Wadena County, then started noticing it near the public water access points on the Crow Wing and Mississippi Rivers, always under tree cover and never in abundance. It may well be under-reported in the state.

Elymus curvatus is distinguished by its erect spike, the base sometimes partially enclosed in the uppermost sheath; 2 spikelets per node; usually 3 or 4 florets per spikelet; glumes and lemmas both short-awned to awnless, sometimes glaucus; both glumes nearly equal in size, 1.2 to 2.1 mm wide, thickened and slightly to strongly bowed at the base; florets and glumes both drop off at maturity; 6 to 9 leaves that are floppy, hairless, up to about 15 mm wide.

Most Elymus species in Minnesota have nodding spikes; of those with erect spikes, most similar is Virginia Wild Rye (Elymus virgunicus); E. curvatus was once lumped with it (E. virginicus var. submuticus, or E. submuticus). Both have 2 spikelets per node, glumes that are bowed at the base and drop off at maturity, but E. virginicus has awns on both glumes and lemmas longer than 5 mm where E. curvatus awns are less than 4 mm and sometimes absent.

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More photos

Photos by K. Chayka and Peter M. Dziuk taken in Wadena County.

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