PORCUPINE GRASS

PORCUPINE GRASS

Hesperostipa spartea
GRASS FAMILY (Poaceae)

Click on each photo thumbnail to enlarge.

This native perennial has flowering stems from 1 1/2 to 4 feet tall. Long, narrow leaves with rolled-up margins are up to 18 inches long and less than 1/8 inch wide. The mature arching flower stems bear long, narrow panicles with drooping clusters of flowers at the branch tips (A). Each flower and, eventually, the maturing seed is enclosed by two pale bracts called glumes. Close-up photo (C) shows empty glumes from which the seed has fallen just above those still enclosing the narrow, 1 inch long seed. Two additional bracts cover the seed. One, the reddish-brown lemma visible in photo (C), has a characteristic sharp-pointed, twisted and coiled bristle-like awn at its tip. The awns are from 4-7 inches long and are responsible for the “brush-like” appearance of the panicle (A) which looks remarkably different after the seeds with their attached awns have dropped leaving only the empty glumes in place (D).

Upland prairies. Porcupine Grass has been identified only at Neale Woods where it is rare in the Nebraska Prairie restoration. It is one of our earliest maturing prairie grasses, flowering in June and July.

The sharp seed tips and long awns can cause injury to grazing livestock and are responsible for names like Needlegrass and Needle-and-thread for other similar members of this genus. The long awns are remarkable self-planting devices, actually drilling into the soil as they coil and uncoil in response to changing moisture conditions.

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