Dichanthelium leibergii (Leiberg's Panic Grass)
Also known as: | Leiberg's Rosette Grass |
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Genus: | Dichanthelium |
Family: | Poaceae (Grass) |
Life cycle: | perennial |
Origin: | native |
Habitat: | sun; moist to dry; prairies, along railroads, open woods, bluffs |
Fruiting season: | June - September |
Plant height: | 10 to 30 inches |
Wetland Indicator Status: | GP: FACU MW: FACU NCNE: FACU |
MN county distribution (click map to enlarge): | |
National distribution (click map to enlarge): |
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Detailed Information
Flower:
Erect branching cluster 2 to 4 inches long at the top of the stem, the branches usually spreading to ascending, sometimes erect, with a few spikelets (flower clusters) per branch, usually fewer than 40 spikelets in a panicle. Spikelets are short-stalked, 3.3 to 4 mm (to ~1/6 inch) long, broadest near the tip, and have 2 florets but appear single-flowered. In summer to fall, few-flowered secondary panicles may form in the lower and mid-stem nodes that may be at least partially hidden in the sheaths.
At the base of a spikelet is a pair of bracts (glumes), the lower glume about half as long as the spikelet, pointed at the tip, the upper glume as long as the spikelet, 7-veined, blunt to rounded at the tip. Surrounding a floret is a pair of bracts (lemma and palea), the lower lemma like the upper glume and usually staminate; the lower palea is insignificant. The upper lemma is fertile, shorter than the upper glume, shiny and hardened, rounded at the tip, the edges rolled around the edges of the similar palea.
The two glumes and lower lemma are all sparsely to moderately covered in hairs .5 to 1 mm long that have an enlarged, pimple-like base (papillose). Magnification recommended.
Leaves and stems:
The 3 or 4 stem leaves are alternate, erect to ascending, straight to somewhat floppy, to 6 inches long, 7 to 15 mm (to ~½ inch) wide, flat, with a long taper to a pointed tip, and at least sparsely hairy on both surfaces plus a few long hairs along the edge near the base, all the hairs papillose-based. In fall, a loose rosette of basal leaves is formed, the leaves similar but somewhat smaller than the stem leaves.
Sheaths are variously covered with spreading to ascending papillose-based hairs. The ligule (membrane where the leaf joins the sheath) is .3 to .5 mm long; a minute fringe of hairs may or may not be present. Nodes are sparsely covered in long papillose-based hairs; uppermost nodes may be hairless. Stems are hairless to minutely hairy, multiple from the base usually forming dense clumps, erect or prostrate from the base and rising at a lower node (geniculate). In summer to fall, plants may become more spreading and sparsely branched from the lower and mid-stem nodes.
Fruit:
The whole spikelet drops away when mature, leaving a naked stem behind. Grains (seeds) are enclosed within the persistent lemma and palea.
Notes:
Dichanthelium, formerly lumped with Panicum, are cool-season grasses with two different bloom periods. The primary bloom is a terminal panicle in spring, the secondary is auxiliary panicles in summer into fall, during which time a rosette of basal leaves may also formed. The two forms can be very different from each other; spring identification is more reliably consistent but this is still a difficult genus.
Dichanthelium leibergii, formerly Panicum leibergii, is most often found in moist to dry prairies, less often in open woods or bluffs. It is distinguished by its (usually) densely clump-forming habit; long hairs with pimple-like bases (papillose) on sheaths, nodes and spikelets; leaves up to about ½ in wide that are erect to ascending and at least sparsely papillose hairy on both surfaces; very short ligule (.3 to .5 mm) that may or may not have a fringe of hairs; panicle usually with ascending to spreading branches, sometimes erect, and fewer than 50 spikelets; spikelets 3.3 to 4 mm long, broadest near the tip, the lower glume half (or more) as long as the spikelet. The secondary bloom is from the lower and mid-stem nodes and branches where the panicles may be only partially emerged; basal leaves are like stem leaves but somewhat smaller. The papillose-based hairs on spikelets is a unique trait but not easily seen without magnification, though in the right light the enlarged bases can give a polka-dotted appearance even without magnification.
Most similar is Dichanthelium oligosanthes (Scribner's Panic Grass), which can have a very similar form with somewhat broad (to ~½ inch) hairy leaves and open, few-flowered panicles, but the ligule is a fringe of hairs 1 to 3 mm long, spikelets are hairless or short-hairy, leaf surface hairs and spikelet hairs lack papillose bases, the lower glume is less than half as long as the spikelet, and the upper glume typically has an orange or purple spot at the base.
D. leibergii plants with contracted panicles may resemble D. xanthophysum (Slender Panic Grass), which is most often found in forested habitats and lacks leaf surface hairs, or D. perlongum (Slimleaf Panic Grass), which has much narrower leaves, only 1 to 3.5 mm wide, and the lower glume is only about 1/3 as long as the spikelet. Both these species also have spikelets with shorter hairs that lack papillose bases.
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More photos
- Leiberg's Panic Grass plant
- Leiberg's Panic Grass plant
- Leiberg's Panic Grass plant
- Leiberg's Panic Grass habitat
- Leiberg's Panic Grass in mid-summer
- flowering panicle in mid-summer
- panicles are sometimes contracted with erect branches
- leaves are at least sparsely hairy on both surfaces
- comparison of Dichanthelium xanthophysum and D. leibergii spikelets
Photos by Peter M. Dziuk taken in Clay, Dakota and Pope counties.
Comments
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