Bouteloua hirsuta (Hairy Grama)

Plant Info
Also known as:
Family:Poaceae (Grass)
Life cycle:perennial
Habitat:sun; dry sandy or rocky soil; prairies
Fruiting season:July - September
Plant height:6 to 30 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: raceme Cluster type: spike

[photo of spike clusters] Raceme-like cluster on the upper stem, 1 to 4 branches, often 2, rarely 5 or 6. Branches are up to 1½ inches long and short-stalked, the terminal branch erect to spreading, the lateral branches ascending to slightly drooping.

[photo of flowering spikelets] A branch has 20 to 50 spikelets (flower clusters), arranged on one side of the rachis (stalk), tightly packed in 2 rows, the tip of the rachis extending 5 to 10mm beyond the terminal spikelet. Spikelets are green to purple, 5 to 6 mm long, each with one fertile and usually one sterile floret, sometimes two.

[close-up of flowering spikelet] At the base of a spikelet is a pair of bracts (glumes) that are smooth to rough textured, pointed or short awned at the tip, the lower glume awl-shaped, 1.4 to 3.5 mm long, the upper glume lance-shaped, 3.5 to 6 mm long, the midvein with long hairs that have pimple-like bases (papillose). The fertile floret is surrounded by a pair of bracts (lemma and palea), the lemma about as long as the upper glume, short-hairy, rough along the midvein, with 1 to 3 short awns; the palea is slightly shorter than the lemma and not awned. Sterile lemmas are stalked, 2-lobed, 3-awned, shorter than the fertile lemmas but longer awned, and are hairless or short-hairy, sometimes with a tuft of long hairs at the base. The second sterile lemma, when present, is reduced to a thin, hairless scale.

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

[photo of leaves] Leaves are basal and along the lower stem, 1 to 12 inches long, 1 to 3 mm wide, flat in cross-section but often with the edges rolled up (involute) especially when dry. Long, white hairs with pimple-like bases (papillose) are usually scattered on both surfaces and along the edges, especially near the base of the blade.

[photo of sheath, ligule and node] Sheaths are mostly hairless, sometimes short-hairy, smooth to slightly rough textured. The ligule (membrane where the leaf joins the sheath) is a fringe of white hairs .2 to .5 mm long. The outer edge of the ligule (collar) is lined with long, white hairs. Nodes are smooth to minutely hairy. Stems are erect, or horizontal but rising at the tip (decumbent), unbranched or branched from the base, hairless, forming loose to dense clumps, and sometimes loose colonies from horizontal stems (stolons).

Fruit: Fruit type: seed without plume

[photo of mature spikelet and grain] Spikelets ripen to light brown, the florets dropping at maturity, leaving the glumes behind. As the florets mature and the spike branch dries, it curls back (recurves) and persists into winter. Grains (seeds) are oblong-elliptic and brown, 2.5 to 2.6 mm long.


Hairy Grama is a dry prairie species that reaches the northern edge of its range in Minnesota. It is easily confused with the related Blue Grama (Bouteloua gracilis), which is less hairy overall, has longer spikes with more spikelets per branch (40 to 130), and the branch rachis does not extend much past the last spikelet (see comparison photo below). There are 2 varieties (or subspecies) of Bouteloua hirsuta: var. pectinata has a limited range in Oklahoma and Texas, 3 to 4 nodes, 3 to 6 flowering branches, mostly basal leaves; var. hirsuta ranges from Minnesota to Mexico, has 4 to 6 nodes, 1 to 4 flowering branches, leaves mostly on the lower stem. While var. hirsuta is said to have mostly decumbent stems, we have not observed this in the field.

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More photos

Photos by K. Chayka taken in Anoka County. Photos courtesy Peter M. Dziuk taken in Dakota and Pope counties.


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

Posted by: Brett W. - Sherburne County
on: 2023-08-12 18:58:53

After the must disturbed area in the (SE Unit) of Uncas Dunes SNA this grass is abundant. It was here before but this seems like a good year too.

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