Koeleria macrantha (Junegrass)

Plant Info
Also known as:
Genus:Koeleria
Family:Poaceae (Grass)
Life cycle:perennial
Origin:native
Habitat:part shade, sun; dry sandy or rocky soil; prairies, savanna, dunes, open woods
Fruiting season:June
Plant height:10 to 20 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: Cluster type: panicle Cluster type: spike

[photo of flowering panicles] Narrow branching cluster up to 6 inches long at the tip of the stem. Branches are alternate, typically less than 1 inch long, spreading to ascending, and hairless or minutely short-hairy.

[photo of spikelets] Along branches are short-stalked spikelets (flower clusters), each containing 2 flowers, occasionally 3 or 4. Spikelets are 5 to 6 mm long, initially green to yellowish green. The 2 glumes (bracts at the base of a spikelet) are unequal in length, the longest slightly shorter than the spikelet. The first glume is up to 4 mm long, the second is proportionately larger, up to 5 mm long. The lemma (2 bracts surrounding the flower) are about the same size and shape as the glumes and rarely awned; the long yellow anthers, 1 to 1.8 mm long, poke out from the sides. The glumes and lemma are all lance-oblong with a sharply pointed tip and a line of short, stiff hairs (scabrous) along an obscure keel (ridge) on the back.

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

[photo of upper stem leaf] Leaves are mostly ascending and near the base of the stem with a few alternate leaves up to about mid-stem. Leaves are up to 6 inches long, 1 to 4 mm wide, flat or rolled along the edges (especially when dry), hairless to finely hairy, and may have sparse, long hairs along the edge near the base.

[photo of sheath and ligule] The sheath is mostly open at the front, typically densely covered in short hairs though may be hairless on the upper stem, and may have sparse, long hairs along the edge. The ligule (membrane where the leaf meets the sheath) is less than 1 mm long and ragged along the top. Nodes are hairless and often hidden by the sheath. The culm (stem) is stiffly erect, hairless to finely short-hairy especially on the lower plant. Plants grow in loose to dense tufts.

Fruit: Fruit type: seed without plume

[photo of mature spikelets] The panicle branches become more erect as fruit develops, forming a slender, light tan spike when mature. When seed is ripe the lemma drop off leaving the glumes behind. Seed is 2.5 to 3 mm long.

Notes:

Junegrass is a circumboreal species, native to much of North America as well as Europe and Asia and as far south as Mexico. It is one of the first prairie grasses to bloom, the pale, narrow panicles readily visible in June, and is where the common name originates. It is a rather variable species particularly in overall hairiness. Similar in form are Wedge grasses (Sphenopholis spp.), which can reach heights of 3 feet or more, prefer moister habitats, and have smooth glumes that drop off with the rest of the spikelet, the first glume very narrow, the second much broader than that of Junegrass and more rounded at the tip. Junegrass sometimes goes by synonym Koeleria cristata (an invalid name) or Koeleria pyramidata.

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More photos

Photos by K. Chayka taken at Moore Lake Dune, Anoka County. Photos courtesy Peter M. Dziuk taken at Grey Cloud Dunes SNA, Washington County.

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