Sphenopholis intermedia (Slender Wedgegrass)

Plant Info
Also known as: Slender Wedgescale
Genus:Sphenopholis
Family:Poaceae (Grass)
Life cycle:perennial
Origin:native
Habitat:part shade, sun; moist to dry; swamps, ravines, floodplains, creek banks, shores, sedge meadows, bluffs, wooded slopes, forest clearings
Fruiting season:July - August
Plant height:1 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: panicle Cluster type: spike

[photo of panicle] Branching cluster 3 to 8 inches long at the top of the stem, the branches erect to slightly spreading, and the panicle often nodding some to one side. Short-stalked spikelets (flower clusters) are overlapping and somewhat crowded on each branch, somewhat flattened, 2 to 4 mm (to 1/6 inch) long, and have 2 or 3 florets.

[close-up of spikelet] At the base of a spikelet is a pair of bracts (glumes), both shorter than the spikelet, keeled, rough along the keel, awnless, the upper glume 2 to 3 mm long, widest near the tip, blunt to pointed at the tip, weakly 3-veined, the lower glume 1-veined, oblong-linear, ¾ to about as long as the upper glume and less than 1/3 as wide. Florets are surrounded by a pair of bracts (lemma and palea), the lemma 2 to 3 mm long, weakly 5-veined, blunt to pointed at the tip, awnless; the palea is membranous, somewhat shorter than the lemma. The thickened base of the floret (callus) is hairless; the stalk between florets (rachilla) is hairless or short-hairy.

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

[photo of sheath, ligule and node] Leaves are alternate, 3 to 6 inches long, 2 to 6 mm (to ¼ inch) wide, mostly flat, smooth to slightly rough-textured, hairless to sparsely hairy. Sheaths are hairless to sparsely hairy. The ligule (membrane where the leaf joins the sheath) is 1.5 to 2.5 mm long, jagged across the top, and lacks fringe of hairs. Nodes are hairless.

[photo of leaf clump] Stems are slender, unbranched, hairless, erect to ascending, sometimes single but usually multiple from the base, forming clumps.

Fruit: Fruit type: seed without plume

[photo of maturing florets and grain] Spikelets turn straw-colored to light brown as they dry and the entire spikelet drops off at maturity leaving the naked stalk behind; sometimes the uppermost floret drops off first. Grains (seeds) are elliptic, amber-colored to brown.

Notes:

Sphenopholis species are cool-season grasses, usually clump-forming, with erect to nodding panicles, spikelets 2 or 3-flowered, unequal glumes both shorter than the spikelet, the lower glume much narrower than the upper, and the entire spikelet dropping off at maturity, sometimes the upper floret dropping off first. The panicle may be open and lemmas are sometimes awned but the two species in Minnesota have mostly erect panicle branches, so can appear more spike-like (though may be nodding), and glumes and lemmas all lack awns.

Slender Wedgegrass (Sphenopholis intermedia) is distinguished from Prairie Wedgegrass (Sphenopholis obtusata) by its upper glume being blunt to pointed at the tip where the latter is more distinctly hood-shaped. Both are usually hairless, sometimes short-hairy, and spikelets are usually less than 4 mm long. Prairie Wedgegrass is more likely to have an erect, spike-like panicle and be found in open prairie-like habitats where Slender Wedgegrass often has a nodding panicle and is more shade-tolerant, found in a wider variety of habitats including bogs, swamps, floodplains, river gorges, bluffs, open woods and wooded slopes. At one time these two were considered vars of the same species, S. obtusata var. major (intermedia) and var. obtusata.

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More photos

Photos by Peter M. Dziuk taken in his garden.

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