Porcupine Grass
Written by Dan Carter. Photos by Dan Carter.
June 22, 2026
Abundant porcupine grass with pale purple coneflower (Echinacea pallida) at Bush Clover Prairie in Grant County, WI.
Porcupine grass (Hesperostipa spartea, AKA needlegrass), one of our most important prairie grasses, is presently beginning to disperse its unique seeds. In Curtis’ The Vegetation of Wisconsin porcupine grass was the most frequently encountered grass in a meter square of mesic prairie, twice as frequent as big bluestem (Andropogon gerardii).
Porcupine grass is a cool-season bunchgrass grass that initiates growth in late March and Early April, flowers in late May/early June, and ripens its fruits in mid-June. The structure and fuels environment it contributes to differs vastly from big bluestem and Indiangrass (Sorghastrum nutans), which have tended to become more abundant on prairies over the last several decades or one-hundred years. Porcupine grass thrives with and contributes to low-intensity, dormant-season fires, and it declines in response to post-green-up burning or with prolonged fire exclusion, which are better-tolerated by big bluestem and Indiangrass.
The long awns of porcupine grass seeds (really grains) curl in response to moisture changes, straightening when conditions are humid, and curling when they are dry. This serves to move them laterally across the soil surface and also to drive the seed into the ground; the latter is facilitated by a very sharp tip and hairs that prevent the seed from backing back out of the soil. Seed is often broadcast fresh, soon after collecting, but in my experience plants will establish from seed planted in fall as well. It seems to establish best when hand-broadcast into existing grassy vegetation burned annually or very frequently in the dormant season to prevent thatch build-up, especially if that vegetation isn’t too dense (if you can see some soil surface down through the grass in midsummer).
Read more about the true prairie grasses here.
Close-up of porcupine grass with seeds that are almost mature.
A tangled ball of porcupine grass seeds in a bag after harvest from a roadside patch in Waukesha County, WI.
Seeds dry upon harvest, causing their awns to curl.
About The Prairie Enthusiasts
The Prairie Enthusiasts is an accredited land trust that seeks to ensure the perpetuation and recovery of prairie, oak savanna, and other fire-dependent ecosystems of the Upper Midwest through protection, management, restoration, and education. In doing so, they strive to work openly and cooperatively with private landowners and other private and public conservation groups. Their management and stewardship centers on high-quality remnants, which contain nearly all the components of endangered prairie communities.