Hesperostipa spartea (Porcupine grass)

Plant Info
Also known as: Needlegrass
Family:Poaceae (Grass)
Life cycle:perennial
Habitat:sun; dry sandy or gravelly soil; open prairie
Fruiting season:spring
Plant height:2 to 4 feet
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

[photo of flowers] Branched cluster 4 to 10 inches long at the top of the stem, sometimes erect but typically nodding, made up of 1 to several side clusters (spikelets) of a few flowers each. The 2 bracts at the base of a spikelet (glume) are about equal in length and ¾ to 1¾ inches long. The 2 bracts surrounding a flower (lemma) are about ¾ inch long, densely covered in stiff hairs at the base, becoming less hairy towards the tip. Attached at the top of the lemma is a 4 to 8-inch long, stiff, needle-like awn covered in very short, stiff hairs. Pistils and stamens poke out between the lemma and are creamy white to pale yellow.

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

[photo of stem leaves] A clump of arching basal leaves, each up to 2 feet long and 3/16 inch wide, surrounds the stem in spring, some of which may wither away by fruiting time. Stem leaves are widely spaced, to 12 inches long, with several distinct veins easily seen on the underside. The leaf sheath edges overlap; sheaths on lower stem leaves may be hairy along the edges but most are smooth. A papery membrane (ligule) at the base of the leaf where it meets the stem is up to ¼ inch long and pointed on upper leaves; on lower leaves it is rounded or straight at the tip and much shorter. Leaves are slightly rough and somewhat hairy on the upper surface, smooth on the lower. Stems are smooth in the lower plant, becoming rough and somewhat hairy in the upper.

Fruit: Fruit type: seed without plume

[photo of fruit] The lemmas mature to medium to dark brown and are released when seed is ripe. The base has a needle-like point and the stiff hairs cause it to attach to anything unlucky enough to pass by. The long awn twists in response to changes in moisture, coiling and uncoiling as it dries, eventually drilling the seed into the ground. Inside the lemma is a slender, cylindric, brown seed about ½ inch long.


There are 2 Hesperostipa (formerly Stipa) species in Minnesota; Hesperostipa comata (Needle-and-thread grass) is generally a smaller plant, with seed essentially ½ to 2/3 the size of H. spartea, lemma drying to light brown, and its awn more slender and more loosely coiling.

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More photos

Photos by K. Chayka taken at Long Lake Regional Park, Ramsey County. Photos courtesy Peter M. Dziuk taken in Anoka and Pope counties.


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

Posted by: Jason - Arlington
on: 2013-07-07 20:09:13

Porcupine grass is giving up it's seeds right now in my area. It is most certainly true how the awns twist in response to moisture differences. Bringing a bag of seeds from the humid outdoors into an air conditioned car is interesting to say the least!

Posted by: Paul - Ottawa Bluffs, a few miles east of St. Peter, LeSueur County
on: 2014-06-09 15:24:12

Saw several of these 7 June 2014 at Ottawa Bluffs, pretty bright green in color, not giving up seeds yet.

Posted by: Kenny h - Mower county Shooting Star Trail
on: 2017-06-18 13:15:31

It is growing very scarcely on railroad prairie remnant, East of Rose Creek...cant see seeds yet...I love this grass.

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