Darnel Ryegrass

This is a noxious arable weed, widespread and naturalized in warm-temperate parts of the world (Darnel). The grains are often infected by a fungus (ergot) which produces the alkaloid temulin, causing poisoning when grazed by cattle or when present as a contaminant of flour.

Awnless or weakly awned variants can be distinguished at varietal rank.

Found throughout its range as a weed of grain crops and is sometimes poisonous to stock. Variants with awnless or short-awned lemmas have been called var. arvense Liljeblad, Svensk Fl., ed. 3, 80. 1816.

In the plains up to 2000 m.

Annual. Culms tufted, erect or decumbent, slender to moderately robust, 20–120 cm tall, 3–5-noded. Leaf blades flat, thin, 10–25 cm × 4–10 mm, smooth or scabridulous on abaxial surface, margins scabrid, young blades rolled; auricles present or absent; ligule 0.5–2.5 mm, obtuse to truncate. Raceme stiff, straight, 10–30 cm; rachis thick, smooth or scabridulous, spikelets about their own length apart. Spikelets turgid, 0.8–2.5 cm, florets 4–10, rachilla internodes 1–1.5 mm, smooth, glabrous; glume linear-oblong, rigid, as long as spikelet, often exceeding florets, 5–9-veined, margins narrowly membranous, apex obtuse; lemmas elliptic to ovate, turgid at maturity, 5.2–8.5 mm, apex obtuse; awn usually present, stiff, scabrid; palea ciliolate along keels. Caryopsis very plump, length 2–3 times width, 4–7 mm. Fl. and fr. May–Aug. 2n = 14.

Annual; culms 20-120 cm high, tufted or solitary, erect or geniculate at the base, slender to moderately stout. Leaf-blades 6-25(-40) cm long, 3-12 mm wide, flat, with short spreading auricles at the base. Spikes erect, 5-40 cm long, rigid, the spikelets their own length or more apart. Spikelets 8-28 mm long, 2-10(-15)-flowered; upper glume 7-30 mm long, 0.75-1.5 times the length of the spikelet, 7-9(-11)-nerved, obtuse; lemmas elliptic to ovate, 4.6-8.5 mm long, smooth, obtuse, very turgid at maturity, awnless or with an awn up to 23 mm long.

Mediterranean region and introduced elsewhere.

Distribution: Pakistan (Baluchistan, Punjab, N.W.F.P. & Kashmir); perhaps native in the Mediterranean region and Southwest Asia; widely introduced elsewhere.

900 m

Fl. & Fr. Per.: April-August.

Fields of cereals, introduced. Anhui, Gansu, Hebei, Heilongjiang, Henan, Hunan, Qinghai, Shaanxi, Shanghai, Xinjiang, Zhejiang [N Africa, SW Asia, S Europe].