Oryzopsis asperifolia (Rough-leaved Rice Grass)

Plant Info
Also known as: Mountain Ricegrass
Genus:Oryzopsis
Family:Poaceae (Grass)
Life cycle:perennial
Origin:native
Habitat:part shade, sun; average to dry rocky soil; open hardwood and mixed forest, Jack pine stands, clearings
Fruiting season:May - July
Plant height:10 to 26 inches
Wetland Indicator Status:none
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 Cluster type: raceme

[photo of panicles] Slender, erect, branching cluster 2 to 4 inches long at the top of the stem. Branches are 1 to 2 inches long, appressed, usually with 2 spikelets (flower clusters) per branch. Spikelets are loosely overlapping at the tip of a branch, short-stalked, narrowly lance-elliptic in outline and have a single floret.

[photo of flowering spikelets] At the base of a spikelet is a pair of bracts (glumes), both about equal in size and shape, hairless, awnless, 6 to 10-veined (more prominent when dry), oblong-elliptic with a blunt or pointed tip, 5 to 8 mm (to 1/3 inch) long and about as long as the spikelet. Florets are surrounded by a pair of bracts (lemma and palea), the lemma leathery, finely hairy, glossy or dull, pale yellowish or greenish or purple-tinged, the body 6 to 8 mm long tapering to a slightly twisted awn 6 to 14 mm (¼ to ½ inch) long, and almost completely wrapping the floret mostly hiding the palea; the palea is slightly shorter than the lemma, 2-veined and sparsely hairy. Surrounding the base of the floret is a tuft of short, stiff hairs.

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

[photo of evergreen leaf clump] Leaves are evergreen, mostly basal, developing in summer, remaining green through winter and the following spring then die off. Basal leaves are 6 to 16 inches long, 3 to 8 mm (1/8 to 1/3 inch) wide, flat or rolled under along the edges (revolute), tapering at both ends, initially erect becoming arching or prostrate, surfaces rough-textured, the upper surface often with a waxy bloom. Stem leaves are few, become progressively smaller, the uppermost leaves reduced to an inch or less long, or essentially bladeless sheaths.

[photo of sheath, node and upper leaf] The sheath is smooth to rough-textured with narrow papery edging. The ligule (membrane where the leaf joins the sheath) is .2 to .7 mm long with a minute fringe of hairs and is sometimes longer on the ends than the middle. Nodes are smooth. Stems are unbranched, hairless, erect or prostrate, sometimes rising at the lower node (genticulate), multiple from the base and forming loose to dense clumps.

Fruit: Fruit type: seed without plume

[photo of mature floret and grain] The glumes become widely spreading as each grain matures, the florets dropping off individually leaving the glumes behind on the stalk. Grains (seeds) are 4 to 6.5 mm long with an abrupt taper to a beak at the tip.

Notes:

Rough-leaved Rice Grass is a common woodland species found in more than half of Minnesota, and one of the earliest blooming grasses. It is distinguished from other grasses by the single, erect cluster of appressed, single-flowered spikelets up to 8mm long, hairless glumes as long as the spikelet that become spreading at maturity, lemmas with long awns, a hairy surface and tuft of hairs around the base of the floret, nearly bladeless upper sheaths, and short ligules with a fringe of minute hairs. The overall form may be similar to Black-fruited Rice Grass (Patis racemosa, formerly Piptatherum racemosum or Oryzopsis racemosa), which has cluster branches that usually become spreading, lemmas that turn black at maturity, hairy nodes, and longer stem leaves with the basal sheaths bladeless or nearly so. Another species that, while not evergreen, has a fairly robust leaf clump in early spring is False Melic Grass (Schizachne purpurascens), which has leaves that are shorter (to 8 inches at maturity) and narrower (3mm or less) and stems with closed sheaths, where Rough-leaved Rice Grass has full-grown (to 16 inches) mature leaves in spring and stems with open sheaths.

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More photos

Photos courtesy Peter M. Dziuk taken in Chisago, Cook, Hubbard, Marshall, Pine, and Washington counties.

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