1. Stipa spartea Trin. (porcupine grass)

Pl. 183 d–f; Map 743

Hesperostipa spartea (Trin.) Barkworth

Flowering stems 45–120 cm long, erect or sometimes arched, glabrous or somewhat hairy at the nodes. Leaf sheaths glabrous except along the margins. Leaf blades 15–65 cm long, 2–6 mm wide, flat or with the margins inrolled, not twisted at the base, the upper surface roughened and usually hairy, the undersurface glabrous or somewhat roughened, the midvein not noticeably thickened. Inflorescences narrow panicles, erect to nodding. Glumes 28–45 mm long, linear‑lanceolate, tapered to a narrowly pointed or short‑awned tip, 5‑ or 7‑nerved, glabrous. Lemma with the main body 15–24 mm long, linear, tapered at the tip to an awn 100–180 mm long that is persistent and not articulated, but spirally twisted when dry (usually coiled twice), brown, not shiny, densely hairy toward the base and along the margins near the tip, with a band of short hairs at the attachment point of the awn, nerveless or nearly so. 2n=44, 46. May–September.

Scattered in the Glaciated and Unglaciated Plains Divisions (Pennsylvania to Montana south to Ohio, Indiana, Missouri, Wyoming, and New Mexico; Canada). Upland prairies; also roadsides and railroads.

Stipa spartea produces both chasmogamous (open‑flowering) and cleistogamous (closed) spikelets, which are similar in appearance. The cleistogamous spikelets have stamens that never become exserted to release their pollen into the air and have shorter anthers (0.3–0.5 vs. 0.5–1.1 mm). The spikelets of this grass can injure the noses, eyes, mouths, and intestines of cattle and other animals that attempt to graze on them, but before flowering the vegetative portions of the plants are palatable and provide good fodder. The awns and narrow lemmas are adaptations for seed dispersal. The awns coil and uncoil as moisture conditions change, screwing the fruit into the ground.