1. Hordeum jubatum L. (squirreltail, foxtail barley)

Pl. 187 c, d; Map 758

Plants perennial, short‑lived, often flowering the first season and thus appearing annual. Flowering stems 30–70 cm long, the nodes dark brownish black. Leaf sheaths glabrous or with spreading hairs. Leaf blades 3–15 cm long, 1.5–4.5 mm wide, roughened or hairy, with a pair of inconspicuous (less than 0.5 mm long) auricles at the base or the auricles absent. Inflorescences 4–10 cm long (excluding the awns), arched or nodding, disarticulating at the nodes of the axis, the joints shed as a unit with the attached spikelets. Spikelet clusters with the central spikelet fertile and the 2 lateral spikelets sterile and with reduced florets. Glumes 25–80 mm long (including the awns), narrow and awnlike throughout, slender, spreading or curved outward at maturity. Lemma of the fertile florets with the body 5.5–8.0 mm long, narrowly elliptic, tapered to an awn (10–)30–70 mm long, the awns slender, spreading or curved outward at maturity. Anthers 1.0–1.5 mm long. Fruits 3.0–3.5 mm long. 2n=14, 28, 42. May–October.

Scattered to common, mostly north of the Missouri River (northern U.S. south to North Carolina, Texas, and California; Canada; introduced in South America, Europe, and Asia). Banks of streams and rivers and edges of marshes; also pastures, crop fields, fallow fields, roadsides, railroads, and open, disturbed areas.

Steyermark (1963) noted, “The young inflorescence of this species sometimes takes on a beautiful rose‑purple color with a glistening effect in the sunlight.” It often occurs as dense populations along roadsides. The awns can injure the noses, eyes, mouths, and intestines of cattle and other species that attempt to graze on the plants, which makes the species undesirable as forage, except when very young.

For a discussion of a sterile hybrid between H. jubatum and Elymus trachycaulus (Link) Gould ex Shinners, see the treatment of that species.