Leersia virginica (White Grass)

Plant Info
Also known as: White Cutgrass, Virginia Cutgrass
Genus:Leersia
Family:Poaceae (Grass)
Life cycle:perennial
Origin:native
Habitat:part shade, shade; moist soil; woods, stream banks, floodplains, wooded ravines, marsh edges
Fruiting season:August - October
Plant height:1 to 4 feet
Wetland Indicator Status:GP: FACW MW: FACW NCNE: FACW
MN county distribution (click map to enlarge):Minnesota county distribution map
National distribution (click map to enlarge):National distribution map

Pick an image for a larger view. See the glossary for icon descriptions.

Detailed Information

Flower: Flower shape: indistinct Cluster type: panicle

[photo of spikelet clusters] Branching cluster at the top of the stem, pyramidal in outline, 4 to 10 inches long with 4 to 8 branches, 1 branch per node. The lowest branches may be partially enclosed in the uppermost leaf sheath. Branches are very slender, 2 to 5 inches long, initially erect becoming ascending to spreading, each with 1 to 3 branchlets that are congested on the upper half or so of the branch and remain tightly appressed to the branch. Spikelets (flower clusters) are arranged all on one side of a branchlet, appressed, initially overlapping but spreading out with age, not overlapping or barely so when mature. Spikelets are short-stalked, oblong-elliptic to narrowly D-shaped in outline, and have a single floret.

[close-up of branch] A pair of bracts (glumes) at the base of a spikelet is absent altogether. Surrounding a floret are a pair of bracts (lemma and palea), both boat-shaped, whitish with green veins, 2.5 to 4 mm (to ~1/8 inch) long and flattened laterally, usually sparsely to moderately hairy along the keels so the spikelet appears fringed all around the outer edge. The lemma is more than ¾ the width of the spikelet, 5-veined and convex along the keel, hairy along the edges like on the keel, sometimes short-hairy on the surface. The palea is 3-veined, straight or nearly so along the keel, occasionally lacking hairs along the keel, is slightly longer than the lemma, and the width is less than ¼ the width of the spikelet.

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

[photo of leaves] Leaves are 2 to 8 inches long, 6 to 15 mm (to ~½ inch) wide, ascending to spreading though somewhat limp, flat, smooth to rough-textured on both surfaces, sometimes hairy on the lower surface, the edges smooth or with a fringe of short, stiff hairs.

[photo of sheath, ligule and node] The sheath is smooth to slightly rough-textured, and often has a pair of small triangular lobes (auricles) at the apex. The ligule (membrane where the leaf joins the sheath) is .5 to 1 mm long, mostly straight across, not fringed with hairs, and joined to the sheath auricles. Nodes are densely hairy with downward pointing (retrorse) hairs. Stems are smooth and hairless to sparsely rough hairy, branched, weak and mostly prostrate from the base then rising near the tip (decumbent) and sometimes rooting at the nodes, single or multiple from the base and forming loose clumps. Plants often form small, tight colonies from short, thick, scaly rhizomes.

Fruit: Fruit type: seed without plume

[photo of individual spikelets] Spikelets turn purplish-brown at maturity, the florets shedding individually as each grain matures, leaving a naked stem behind. Grains (seeds) are reddish-brown, 2 to 2.4 mm long.

Notes:

Leersia virginica reaches the northern edge of its range in Minnesota, found in moist woods, wooded ravines, floodplains and wooded stream banks in the southern half of the state. While from a distance, Leersia virginica may resemble other grasses with a few-branched panicle, such as Glyceria borealis (Northern Manna Grass), a closer inspection of the spikelets shows how different the Leersia species are: the single-flowered spikelets congested at branch tips, lacking awns and flattened laterally, with conspicuous hairs along the keel of both lemma and palea, along with the absence of glumes are a unique combination, and all 3 Minnesota Leersia species also have densely hairy stem nodes. Leersia virginica is distinguished from the other 2 by having panicle branches all single at the nodes, spikelets 2.5 to 4 mm long, shaped similarly to a grain of rice, and are not much overlapping on the branchlet if at all, especially towards the tip. By comparison, Leersia lenticularis (Catchfly Grass), a rare species of floodplain forest, has nearly round spikelets that are much overlapping on their branch, and Leersia oryzoides (Rice Cutgrass) has more heavily branched panicles with 2 or more branches at the lower nodes, spikelets 4 to 6 mm long that overlap about half their length.

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More photos

Photos courtesy Peter M. Dziuk taken in Anoka, Renville and Rice counties.

Comments

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

Posted by: Molly R - Nicollet county on top and in small but steep ravine leadin
on: 2017-07-27 22:46:00

In my shady and damp yard and occasionally in the forest around here. I have some photos if needed

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